How to navigate from an activity to a fragment of another activity of a navigationBar?

Good morning

I have a problem in the navigation of my application in which I have a mainActivity (); where I have a series of fragments, now create a form activity in which for the moment I just need the one button to return me to a specific fragment of the activity that has the NavegationBar that contains the series of fragments.

This is the MainActivity with the navigationBar:

 public class MainActivity extends AppCompatActivity implements HomeFragment.OnFragmentInteractionListener,ProfileFragment.OnFragmentInteractionListener,TasksFragment.OnFragmentInteractionListener,GroupsFragment.OnFragmentInteractionListener {

    private BottomNavigationView bottomNavigationView;
    //private TextView titleView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate ( savedInstanceState );
        setContentView ( R.layout.activity_main );


        // Forzar y cargar icono  en el action bar
        getSupportActionBar ().setDisplayShowHomeEnabled ( true );
        getSupportActionBar ().setIcon ( R.mipmap.ic_to_do_round );

        //inicializar con un fragmento
        HomeFragment homeFragment = new HomeFragment ();
        FragmentTransaction transaction = getSupportFragmentManager ().beginTransaction ();
        transaction.replace ( R.id.fragment_container,homeFragment);
        transaction.commit ();

        // manejo de bottomNavegationView
        bottomNavigationView = (BottomNavigationView) findViewById ( R.id.navigation );
        //titleView = (TextView) findViewById ( R.id.title_home );

        bottomNavigationView.setOnNavigationItemSelectedListener ( new BottomNavigationView.OnNavigationItemSelectedListener () {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                if (item.getItemId () == R.id.action_home) {
                    HomeFragment homeFragment = new HomeFragment ();
                    FragmentTransaction transaction = getSupportFragmentManager ().beginTransaction ();
                    transaction.replace ( R.id.fragment_container,homeFragment);
                    transaction.commit ();
                    //titleView.setText ( "Home" );
                } else if (item.getItemId () == R.id.action_profile) {
                    ProfileFragment profileFragment = new ProfileFragment ();
                    FragmentTransaction transaction = getSupportFragmentManager ().beginTransaction ();
                    transaction.replace ( R.id.fragment_container,profileFragment);
                    transaction.commit ();
                    //titleView.setText ( "Profile" );
                } else if (item.getItemId () == R.id.action_task) {
                    TasksFragment tasksFragment = new TasksFragment ();
                    FragmentTransaction transaction = getSupportFragmentManager ().beginTransaction ();
                    transaction.replace ( R.id.fragment_container,tasksFragment);
                    transaction.commit ();
                    //titleView.setText ( "Tasks" );
                } else if (item.getItemId () == R.id.action_group) {
                    GroupsFragment groupsFragment = new GroupsFragment ();
                    FragmentTransaction transaction = getSupportFragmentManager ().beginTransaction ();
                    transaction.replace ( R.id.fragment_container,groupsFragment);
                    transaction.commit ();
                    //titleView.setText ( "Groups" );
                }

                return true;

            }
        } );
    }

    @Override
    public void onFragmentInteraction(Uri uri) {

    }
}

This is the fragment where you communicate to that activity by pressing a button:

    public class TasksFragment extends Fragment {

    ListView listTasks;
    ArrayList<TaskInformation> listaDeInformacionDeLasTareas;

    android.support.design.widget.FloatingActionButton floatingActionButton;

    private OnFragmentInteractionListener mListener;

    public TasksFragment() {
        // Required empty public constructor
    }


    // donde se pasan las variables de un fragmento a otro y donde se crean las partes logicas
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate ( savedInstanceState );
        if (getArguments () != null) {

        }
    }

    //donde se crean las partes visuales del fragmento
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View view = inflater.inflate ( R.layout.fragment_tasks, container, false );

        //Floating button
        floatingActionButton = (FloatingActionButton) view.findViewById ( R.id.fab );
        floatingActionButton.setOnClickListener ( new View.OnClickListener () {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent (TasksFragment.this.getActivity (),TaskFormActivity.class);
                startActivity (intent);
            }
        } );

        //lista de tareas en el fragmento
        listTasks = (ListView) view.findViewById ( R.id.list_view_tasks );
        listaDeInformacionDeLasTareas = new ArrayList<TaskInformation> ();

        listaDeInformacionDeLasTareas.add ( new TaskInformation ( 1, "Realizar informe de reunion general", "00-00-0000", "Business" ) );

        AdapterTask adapterTask = new AdapterTask ( TasksFragment.this.getActivity (), listaDeInformacionDeLasTareas );
        listTasks.setAdapter ( adapterTask );

        return view;
    }

    // TODO: Rename method, update argument and hook method into UI event
    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onFragmentInteraction ( uri );
        }
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach ( context );
        if (context instanceof OnFragmentInteractionListener) {
            mListener = (OnFragmentInteractionListener) context;
        } else {
            throw new RuntimeException ( context.toString ()
                    + " must implement OnFragmentInteractionListener" );
        }
    }

    @Override
    public void onDetach() {
        super.onDetach ();
        mListener = null;
    }


    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        void onFragmentInteraction(Uri uri);
    }
}

This is the activity where I am and I want to go to the TaskFragment fragment:

    public class TaskFormActivity extends AppCompatActivity {

    Button btnFormCreate;
    Button btnFormCancel;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate ( savedInstanceState );
        supportRequestWindowFeature ( Window.FEATURE_NO_TITLE );
        setContentView ( R.layout.activity_task_form );

        btnFormCreate = (Button)findViewById ( R.id.btn_form_create );
        btnFormCancel = (Button)findViewById ( R.id.btn_form_cancel );

        btnFormCreate.setOnClickListener ( new View.OnClickListener () {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent (TaskFormActivity.this,MainActivity.class);
                startActivity (intent);
            }
        } );

        btnFormCancel.setOnClickListener ( new View.OnClickListener () {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent (TaskFormActivity.this,MainActivity.class);
                startActivity (intent);
            }
        } );


    }
}

Greetings