Hey so first off i would like to point out that I know that there are several other questions about this topic up here, I have even done this exact thing myself before. I am ask
Add your user control to the form:
home.Controls.Add(t_ES);
Either make entry suggestion inherit the form class or add it to an existing form using form.Controls.Add. Remember, it's a user control, not a user form, thus it cannot support itself, it needs a container and ultimately it has to have a form containing it somewhere.
You need to add your user control to the display surface of the main form (or another container already present)
MainScreen home = new MainScreen();
home.Show();
EntrySuggestion t_ES = new EntrySuggestion();
home.Controls.Add(t_ES);