Ok so you just wanna level up in co-op with a friend? Don't bother trying to figure out hamachi or private games its very random. Some say it works but I couldn't do it was a huge headache. If you just wanna play without getting slaughtered and level up and stuff its fairly simple just follow these easy steps.

First you will want to configure the key mappings however the devs apparently know nothing about keyboards or fps games.

Anyway once that's done in sp, I suggest playing through the tutorial level and getting to the HQ building before starting online.

So go to the menu and where it says join server.
Right click on a co-op server and go to view server info like on the screen shot.


IMPORTANT

See where it says SBO, if you see that in info RUN, Backout, get away, don't do it. If you are a newb you will die over and over again. SBO means the enemies accuracy is through the roof they will kill you fast and you and your friend won't have any fun.


This is the server you want if you are a beginner. I'm not sure what the difficulty actually is, but its not crazy as hell. Now on the same right click menu you used to inspect the games, you can add it to favorite servers.

Also if you played SP and got through the turtorial or even a few missions and want to resume online, talk to this guy.

Select yes then go through the portal, you will be back at whatever point you finished in SP or other online campaigns.

Now you can play and have fun with friends anytime you want.

Hope this helps its not really as obvious as it should be, but its a simple process once you know how. Enjoy and have fun.