public static final String MyPREFERENCES = "MisPreferences" ;
public static final String userName = "nombreUsuario";
public static final String userPassword = "passwordUsuario";

String username  = userName.getText().toString();
String password  = passwordUser.getText().toString();

SharedPreferences.Editor editor = sharedpreferences.edit();

editor.putString(userName , username);
editor.putString(userPassword , password);
editor.commit();
//redireccionas por ejemplo a otra Activity
perfil = new Intent(MainActivity.this,second_main.class);
startActivity(in);

SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
String username = getResources().getString("nombreUsuario");