Installation Instructions:
1. Download and unzip one of the above files to your Steam\SteamApps\account\sourcesdk\bin folder.
2. Open Hammer, then go to Tools --> Options.



3. Use the first drop-down menu to choose the game that corresponds to the fgd you downloaded, then highlight the current fgd listed in the Game Data Files box.
4. Click the "Remove" button next the Game Data Files box to remove the old fgd.
5. Click the "Add" button next to the Game Data Files box and browse to the location of the FGD you just downloaded.