create popup message box using c# window application

Is this for the same thing as in show message box when cursor move to next textbox except using different words?

If you want to show a message as part of data validation (in other words, when teh message is not valid) then that is called validation and you will get better answers if you say you need to do validation.

 have you tried MessageBox.Show("your message here");

or you are looking for something different??