Counter Strike: Global Offensive
Before you start
Game Server Login Token
If you wish to run this server outside of your private network (required by Steam for any servers running outside of your home LAN), you will need to get a game server login token.
Registering Game Server Login Token
Manually Configuring Settings
You can go to the official docs to see what you can change. Just replace the config files with what you want and restart the server.
All of these files can be found and edited in the server's local storage path.
./peon/servers/[game_uid]/[server_name]/
Stand-alone mode
Or... just use PEON. it should do all the heavy lifting for you.
Links
If you want to dig a bit deeper, here are the links