I just found out about this game and I need a manual type thing to figure out what I'm doing. I play UT, UT2K4 and Serious Sam, so it's not that I'm new to this type of game, but to jump in not knowing what I'm working with can be a bummer.

Oh yah, from what I've done so far, It's A Great Game!!

Hi and welcome..

You mean something like this: http://forums.alientrap.local/viewtopic.php?t=1344 ?
I guess you can figure out that 'join' takes you to the server browser were you can join online games like in other games.. 'create' lets you create a listen server to play with bots or create a temporary server for you and friends..
'instant action' and 'campaign' takes you on some maps against bots..
'options' should be self explaining

And other stuff like the hud, weapons and maps.. well its explained a bit in that link but it should be easy to figure out..

Or just ask here if something is unclear.. we'll help you