How do I change models?

Garry's Mod general
#1

Since i dont have the model for money in darkrp, i wanted to change it to this money model i downloaded.

Is that even possible.

And to change models, where do you:

  1. find the model you want to change it to,

  2. and what do you edit in the lua to change it.

#2

Is it for a server? If yes you need to get hold of the servers lua.