How do I install and use mods in Steam?
If you have a Half-Life mod installed before installing Steam, Steam will automatically convert and install the game for you. It will then be accessible in the Steam “My Games” list under “Third Party Games.” If you want to add a mod after installing Steam, you need only to put it in the Steam/SteamApps/your_email_address/Half-Life directory. The next time you open the “My Games” list it will be listed under “Third Party Games.
