Server help

Ok on my gmod server i am using dedicated hosting but how do i change the gamemode my server appears as in the server list? you know when you go on find multiplayer server and it comes up with all the gamemodes how do i make my server appear under a custom gamemode selection thing. Help much appreciated

Please use google next time. There are so many threads on this. Try this anyway. http://www.youtube.com/watch?v=DpGGWjmyt2s