How do I use L4D stuff?

Hi, I’m just starting to play around with Gmod, and I own both l4d and l4d2 and the props/ragdolls from them don’t appear in my game. Do I have to do something to activate them, or do I have to download them? And if so, are there some large packs for them. Thanks in advance; looking forward to producing some interesting things in Gmod and seeing what the community can do :3

gm_mount2, google it.
Dinkleburg…

Ooh, thank you very much! Wonder if that will allow me to use Bloody Good Time models… That game could actually still have a use…