Take the bit ur pc/laptop has 32-bit or 64-bit Thats the newest release i dont think thell be making any other versions sooner or later
WAD files other mods ull need to find out on ur own so lets begin What ull be downloading is called GZDoom u might be asking what is this thing ur talking about its a mod runner u need to download this to able to play mods but the mods ur can run on this must be. The mod runner is something that u really need