Installing Custom Content

http://support.steampowered.com/cgi-bin/steampowered.cfg/php/enduser/std_adp.php?p_faqid=17

You can drop in custom files, like the CS Fusion Pack, into your Steam/SteamApps/<username>/Counter-Strike/ directory.

Steam will use the customized files on disk instead of the ones in the Steam cache file. Important Note

You must not copy over any of the old "Stock Maps" to your Steam Installation.

If you do, you will receive error messages - i.e. "Your Map Differs from the Server's" or "Bad Surface Extents" or other errors referencing missing sprites or models.

Another common error message related to moving stock models, sprites, and maps is "You have been disconnected from the server. Reason: Bad file Server is enforcing file consistency"

In each case the solution is to delete the offending content from the game's folder.

Your Steam installation uses the same basic file structure for all the maps and things once you get to the MOD folder, for example Counter-Strike is typically found here:

C:\Program Files\Steam\SteamApps\<username>\Counter-Strike\cstrike\ or C:\Program Files\Valve\Steam\SteamApps\<username>\Counter-Strike\cstrike\