>Iwads are the game's files, its code, graphics, and everything else that the port needs to run. Download the ones for The Ultimate Doom, Doom II, Plutonia and TNT. Put these in the folder where you installed Crispy Doom.
I think there should just be a zip where these come pre installed. Explaining and expecting users to follow through these steps seem hard when they can just download a zip & unzip it and start teh gaem