Addon Models

I can’t seem to find where to put the models (or maybe it’s a texture problem) for addon weapons. I put them in a folder called “models” that I made (there was no Model folder) in garrysmod/garrysmod. The weapons don’t show up as Error messages but they don’t look like they should, they’re all just checkered purple and black. What can cause this and how should I go about fixing it?