Gamemode Help?

So I have this gamemode and I want to use it can I just place the STGamemodes folder in the garrysmod/gamemodes and then set the gamemode to that. Would that work if it wont can someone help me out?

Just take the gamemodes in the STGamemodes folder and place them in garrysmod/gamemodes.

But then how can I make them all change like fretta because I have no clue how to use fretta;/