How to extend Activity in main class that extends "Fragment"?

I have an Android project and I use Navigation Drawer in it, and in the MainActivity, I have a switch-case, with options and your respective positions for to open when the user clicks. But, in a class called TelaQUEMSOMOS, the parameters that are there:

public class TelaQUEMSOMOS extends Fragment {

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.telaquemsomos, container, false);
        return rootView;
    }
}

are extending from Fragment and not Activity. It's bad, because I need to put a Toast.makeText or findViewById, and I can't. How can I handle it?

In your fragment you can call getActivity() to get instance of the activity.