How can I inherit a variable that gets data with a SQLServer query?

I would like to know how to inherit a variable that contains the ID of a user obtained with the login to make an insertion to the BD with the id of the user that is logged in.

I have tried it in many ways but I have not solved my inheritance problem.

FATHER CLASS:

public class USUARIOS
{
    private string u_;
    private string p_;
    private int id_;

    //public string u { get; set; }
    //public string p { get; set; }
    //public int id { get; set; }

    public string u
    {
        get { return u_; }
        set { u_ = value; }
    }
    public string p
    {
        get { return p_; }
        set { p_ = value; }
    }
    public int id
    {
        get { return id_; }
        set { id_ = value; }
    }
    public USUARIOS()
    {

    }

    public USUARIOS(string no_usu, string pass,ref int i)
    {
        this.u = no_usu;
        this.p = pass;
        this.id = i;
    }

    public void log(string puesto)
    {
        if(puesto=="empleado"){
            MessageBox.Show("Hola Empleado "+u+" "+id);
            SistemaEmpleado pass = new SistemaEmpleado();
            pass.Show();
        }
        else if(puesto=="admin")
        {
            MessageBox.Show("Hola Admin "+u+" "+id);
            SistemaAdmin pass = new SistemaAdmin();
            pass.Show();
        }
        else 
        {
            MessageBox.Show("No se puede acceder");
        }
    }

SON CLASS

public class Empleado : USUARIOS
{
    Conexion x = new Conexion();

    //int i;
    //string name,pass;

    //private string nu;
    //private string ps;
    //private int idd;

    string nu { get; set; }
    string ps { get; set; }
    int idd { get; set; }

    public Empleado(string n, string p,ref int id)
        :base(n,p,ref id)
    {
        //this.nu = n;
        //this.ps = p;
        //this.idd = id;
    }

    public Empleado()
    {

    }
    public Empleado(string u, string p, int id)
    {
        this.nu = u;
        this.ps = p;
        this.idd = id;
    }
    //-------------------------------------------------------------------------------------------------------------------------------------------
    public void add_tck(int id, string equipo, string falla)
    {
        string cadena = "Insert into tickets values ('" + id + "','" + equipo + "','" + falla + "')";
        x.addbd(cadena);
    }
}

BUTTON TO MAKE INSERTION:

    private void iTalk_Button_21_Click(object sender, EventArgs e)
    {
        //string n = "", p="";
        //int i = 0;

        Empleado x = new Empleado();
        USUARIOS u = new USUARIOS();

            DialogResult result = MessageBox.Show("              Desea registrar el reporte?", "Confirmacion", MessageBoxButtons.YesNo);
            if (result == DialogResult.Yes)
            {

            int id = u.id;

            //string equipo = iTalk_ComboBox1.Text;
            //string falla = iTalk_RichTextBox1.Text;
           //int i = u.id;
            x.add_tck(id,iTalk_ComboBox1.Text, iTalk_RichTextBox1.Text);

            }
            else if (result == DialogResult.No)
            {
                //MessageBox.Show("Bye");
                //Close();
            }
    }

CONNECTION CLASS:

public class Conexion
{

    //public string ServidorSQL { set; get; }
    //public string BD { set; get; }
    //-------------------------------------------------------------------------------------------------------------------------------------------
    public void datos(ref int id, ref string puesto, ref string nombre, ref string pass)
    {
        string cadena = "select id_u, puesto, nombre, pass from usuarios where nombre='" + nombre + "' and pass='" + pass + "'";

        SqlConnection carretera = new SqlConnection();
        carretera.ConnectionString = @"Data Source=ZBASS-PC\ZBASS;Initial Catalog=sys_tck;Integrated Security=True";
        //carretera.ConnectionString = "data source=" + ServidorSQL + "; initial catalog=" + BD + "; integrated security=true";
        SqlCommand P = new SqlCommand();
        SqlDataReader contenedor1;
        try
        {
            carretera.Open();
            P.Connection = carretera;
            P.CommandText = cadena;
            contenedor1 = P.ExecuteReader();
            contenedor1.Read();
            id = contenedor1.GetInt32(0);
            puesto = contenedor1.GetString(1);
            nombre = contenedor1.GetString(2);
            pass = contenedor1.GetString(3);
            carretera.Close();
        }
        catch (Exception t)
        {
            carretera = null;
            MessageBox.Show("Error :" + t.Message);
        }
    }
    //-------------------------------------------------------------------------------------------------------------------------------------------
    public void addbd(string cadena)
    {
        SqlConnection Servicios = new SqlConnection(@"Data Source=PCAllINONE;Initial Catalog=sys_tck;Integrated Security=True");
        SqlCommand DB = new SqlCommand();
        try
        {
            Servicios.Open();
            DB.CommandText = cadena;
            DB.Connection = Servicios;
            DB.ExecuteNonQuery();
            MessageBox.Show("Exito, su reporte sera revisado por un administrador.");
            Servicios.Close();
        }
        catch (Exception t)
        {
            Servicios = null;
            MessageBox.Show("Error: " + t.Message);
        }
    }