After you got the console working, here are some cheats you can type in:

1)sv_friction-makes it how fast you go on the ground. You must activate the sv_cheats 1 first.

2)Changelevel ??-to change the level you are on if it is your own server. Fill the ?? with the name of the level.

3)mp_allowmonsters-If you are doing a level from another mod, or trying to see the monsters, this will activate them, but you must restart the level after you type it in.