GMod 13 crashing help

I really need help. After I downloaded GMod 13 beta, I keep getting an errir that says Engine Error: Failed to load Library client"

I went to go see about **[G.AddCSLuaFile

http://wiki.garrysmod.com/favicon.ico](http://wiki.garrysmod.com/?title=G.AddCSLuaFile)** but it doesn’t explain where to do, just what it does. I’m sorry if I don’t see it I’m not used to all this stuff. Please help me