Skinning (VMT iusses)

I’ve been redoing some skins for Gmod and I also have been reskinning some skins(Personal skins). VTFs I do fine with, its the VMT files that confuse me on some parts.

Im wondering which of the 3 lines for the VMT file I would need to link to a different skin? If theres more information about VMT file creation, please advise.

	"$basetexture"	"models\props\cs_assault\billboard"
	"$envmap" "env_cubemap"
	"$envmapmask" "models\props\cs_assault\billboard_ref"


“$basetexture” “models\props\cs_assault\billboard”

Here’s a nice page -