Are you saying when your creating your hack, and that if someone injects your hack in, you want a message box popping up?
If that's the right thing you're looking for, then read below.
Somewhere in the middle of your SndDrv.dll coding, you have to add this after Open File Dialog:
Code:MessageBox.Show("YOU CAN TYPE ANYTHING HERE THAT YOU WANT TO BE SHOWN IN MESSAGE", "THIS IS THE TITLE OF THE MESSAGEBOX")