You would need to "exec" them somewhere. You didn't say what engine... in TGE/TGEa that "somewhere" is usually in the client script init.cs in function initClient()
exec("./ui/yourGUIName.gui");
./ui/ indicates the filepath to which you saved your gui.
Associate Michael Hall
Distracted...
exec("./ui/yourGUIName.gui");./ui/ indicates the filepath to which you saved your gui.