Addon Creation (Garry's Mod)

Help create an addon if you can step-by-step instructions with pictures or video, this mainly applies only to movable objects: NPCs, player skin and weapons.

Here's an example with a weapon: http://www.youtube.com/user/TheMostUpset

I'm not asking you to help me get the models out of the game, I'll figure it out myself, I just need to figure out how to push the model into the addon along with animation and animated textures.