/vr/ - Retro Games

Hi people, I've got a couple of questions regarding the internal files of WADs and google hasn't helped me.
I want to set a text screen at the end of my map but I'm not too sure how to trigger it (the switch at the end of my level has the action End Game)

Also, I've replaced Interpic.png but the game still shows a black screen. I have indexed the image and all that.