DRD Team

I have downloaded gzdoom, launched gzdoom.exe and got this window. How can I launch some arbitrary wad from my PC?

Drag and drop the wad on top of GZDoom to start it. By default most wads use Doom 2 so that should be fine for starting the game, unless the wad specifically states otherwise (or it uses an E#M# mapping scheme in the text file). Since you're using the BFG edition, all Doom 2 mods will exist in the "Hell on Earth" campaign.

http://zdoom.org/wiki/Installation_and_ ... n_of_ZDoom
This applies to GZDoom as well.