How to connect from my MainActivity to About Us (Activity) in Kotlin

Well, my question is how can I connect from MainActivity where I have the following selector:

override fun onNavigationItemSelected(item: MenuItem): Boolean {
    // SELECCIÓN DEL NAV DRAWER
    when (item.itemId) {
        R.id.nav_inicio -> {
            replaceFragmenty(
                    fragment = Fragment1(),
                    allowStateLoss = true,
                    containerViewId = R.id.mainContent
            )
            title = "Incio"
        }
        R.id.nav_web -> {
            replaceFragmenty(
                    fragment = Fragment2(),
                    allowStateLoss = true,
                    containerViewId = R.id.mainContent
            )
            title = "Página Web"
        }
        R.id.nav_proyectos -> {
            replaceFragmenty(
                    fragment = Fragment3(),
                    allowStateLoss = true,
                    containerViewId = R.id.mainContent
            )
            title = "Proyectos"
        }
        R.id.nav_comerciate -> {
            replaceFragmenty(
                    fragment = Fragment4(),
                    allowStateLoss = true,
                    containerViewId = R.id.mainContent
            )
            title = "Comercia-te"
        }
        R.id.nav_eventos -> {
            replaceFragmenty(
                    fragment = Fragment5(),
                    allowStateLoss = true,
                    containerViewId = R.id.mainContent
            )
            title = "Eventos"
        }
        R.id.nav_conocetubarrio -> {
            replaceFragmenty(
                    fragment = Fragment6(),
                    allowStateLoss = true,
                    containerViewId = R.id.mainContent
            )
            title = "Conoce tu barrio"
        }
        R.id.nav_sobrenosotros -> {
            replaceFragmenty(
                    fragment = SobreNosotros(),
                    allowStateLoss = false,
                    containerViewId = R.id.mainContent
            )
            title = "Sobre Nosotros"
        }
        R.id.nav_ajustes -> {
            replaceFragmenty(
                    fragment = Fragment8(),
                    allowStateLoss = false,
                    containerViewId = R.id.mainContent
            )
            title = "Ajustes"
        }
    }

    drawer_layout.closeDrawer(GravityCompat.START)
    return true

I want to connect in the area of:

            R.id.nav_sobrenosotros -> {
            replaceFragmenty(
                    fragment = SobreNosotros(),
                    allowStateLoss = false,
                    containerViewId = R.id.mainContent
            )
            title = "Sobre Nosotros"
        }

With an Activity instead of with a Fragment like in the others, where would have all the content that I want to be shown in my application. In About Us, which is an Acivity) would have the following:

@SuppressLint("Registered")
class SobreNosotros : AppCompatActivity() {

internal lateinit var list: ListView
internal lateinit var titleId: Array<String>
internal lateinit var subtitleId: Array<String>

internal var imageId = arrayOf(R.drawable.inicio, R.drawable.web, R.drawable.proyectos, R.drawable.comerciate, R.drawable.conocetubarrio, R.drawable.eventos, R.drawable.ajustes)

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.fragment_fragment8)

    val toolbar = findViewById<Toolbar>(R.id.toolbar)
    setSupportActionBar(toolbar)
    val actionBar = supportActionBar
    if (actionBar != null) {
        supportActionBar!!.setDisplayHomeAsUpEnabled(true)
        supportActionBar!!.setDisplayHomeAsUpEnabled(true)
        supportActionBar!!.setTitle(R.string.title_about)
    }

    titleId = resources.getStringArray(R.array.title)
    subtitleId = resources.getStringArray(R.array.subtitle)

    val adapter = AdapterList(this@SobreNosotros, titleId, subtitleId, imageId)
    list = this.findViewById(R.id.list)
    list.adapter = adapter
    list.onItemClickListener = AdapterView.OnItemClickListener { parent, view, position, id ->
        if (position == 4) {
            val sendInt = Intent(Intent.ACTION_SEND)
            sendInt.putExtra(Intent.EXTRA_SUBJECT, getString(R.string.app_name))
            sendInt.putExtra(Intent.EXTRA_TEXT, getString(R.string.app_name) + "\n" + getString(R.string.share_content) + "\n" + "https://play.google.com/store/apps/details?id=" + packageName)
            sendInt.type = "text/plain"
            startActivity(Intent.createChooser(sendInt, "Comparte"))
        }
        if (position == 5) {
            val appName = packageName
            try {
                startActivity(Intent(Intent.ACTION_VIEW, Uri.parse("market://details?id=$appName")))
            } catch (anfe: android.content.ActivityNotFoundException) {
                startActivity(Intent(Intent.ACTION_VIEW, Uri.parse("http://play.google.com/store/apps/details?id=$appName")))
            }

        }
        if (position == 6) {
            startActivity(Intent(Intent.ACTION_VIEW, Uri.parse(getString(R.string.more_apps))))
        }
    }

}

override fun onOptionsItemSelected(item: MenuItem): Boolean {
    when (item.itemId) {
        android.R.id.home -> {
            // app icon in action bar clicked; go home
            this.finish()
            return true
        }
        else -> return super.onOptionsItemSelected(item)
    }
}

override fun onBackPressed() {

    super.onBackPressed()
}

}

That is supposed to show a list of data and so on within my application