How do i play Garrys mod 9 I installed it correctly and its on steam i have hl2 hl2 ep 1 hl2 ep 2 and hl2 lost coast and when i go to the main screen and click on buttons nothing works please help

If you are running on Windows Vista or higher, please run the program as an administrator. Also, make sure you are launching the game through Steam, nothing else will work! If none of these work, I highly recommend you uninstall, redownload, and reinstall the program through Steam instead of fiddling around with the settings and messing up your whole Steam Engine.