SO these are really basic, but I don't know the answers to them, so
1- How do you play online against other people? I am used to Halo and using the matchmaking option to search for games, but I am unfamiliar with how to search or play with friends against others on Brink. SO help there would be great.

2- How do you wall jump with a light character? I have tried running at the wall briefly then looking in a another direction hoping to kick off of it after jumping at it or something and I have yet to accomplish this feat, so how do you wall jump? And also how do you know if you have or not?

1 - Best way I find is to go to 'Freeplay' and select 'Competitive' from one of the side options that appears when you get in to that menu (i forget the title of the section, sorry) However there is a similar option going through the 'Campaign' menu at the top, presumably allowing you to pick a map and team to start as.
2 - Jump when in contact with a wall

1- Go to freeplay, choose your "matchmaking" settings in drop out menu and start it up. Or go to campaign, choose a mission, set your visibility (solo, private, public) and gametype (coop, versus) and start it up.

2- Running to or along a wall hit jump twice or smart and jump when you run up the wall a bit. It might take a few tries to get the feel of it (angles and whatnot). Also your character icon at the bottom center of the screen will indicate exactly what your character is doing at the moment. Wall jumping will show a wall next to your toon icon kinda pushing off and up from it (bad terminology there, sorry).