If you're just looking to host a normal game then you need to make sure you have the command sv_pure
set to 0. If you don't know how to do that then you need to open the console (usually by pressing ` which is the button underneath escape on most keyboards I know) and typing in /set sv_pure 0
If you want to host a game with a mod such as Jaymod, then it gets a little more complicated. You need to make sure you have Jaymod loaded, there's a handy mod menu for that on the main menu. You also need to make sure that the file "qagame_mp_x86.dll" is in your Jaymod folder in your game directory. Your game directory is normally C:\Program Files (x86)\Wolfenstein - Enemy Territory
and there will be a folder named Jaymod where the file "qagame_mp_x86.dll" needs to be. If you don't have that file, you'll need to download Jaymod
, find that file and add it.
If you need anything else, ask.