Garry's Mod dont see contents

I bought today Orange box for Garry’s Mod when i laught the game and start the game and the game still washed out like i dont have Half life 2
Help pls

Where is HL2 installed to?

Garrys on C;
Half life 2 on G;

[editline]22nd June 2014[/editline]

Help pls

Garry’s Mod can’t recognize games across harddrives iirc. It only searches the steamapps/common folder on it’s local harddrive.