Nexus Gamebase Problem

Okay, So I just downloaded Nexus Skeleton. I have a problem.
I put it into gamemodes and did all it said on the read me’s. When I type changegamemode gm_atomic Skeleton(Or what ever Novus Two ect.) It comes out as BASE GAMEMODE. Everyone I ask they say I HAVE TO BUY THERE HELP cause them explaining it to me wastes 10 minutes of there life… (Ripoff artists) And I dont have any money, Im geting a job in a year or two but I dont want to wait till then. Please help.
Also, I ask a bunch of people on here and they say YOU NEED TO REMOVE THE BACKDOORS, I ask WHAT ARE THE BACK DOORS? They say FIND OUT YOURSELF. Please help or give me a fixed version of nexus. Or if you can, Post a video tutorial.