Cry Of Fear Sweps Help

Not really sure where this would go, but i cant find any other place.

I need some help making it so i can make sweps from other games, for example cry of fear. (half life 1 mod)

I tried simply taking the models and putting it into a weapon lua file thing but i get an error whenever i try to spawn them (forgot what the error was)

So im asking how would i get half life 1 weapons into gmod.