If you're playing on a Xbox-like gamepad, the default mapping for the social quick menu is d-pad left. If you're going it on a keyboard, hit F4. You can access your friends list from that menu. DCUO, it seems, was designed to be played on a controller. Being one who favors controllers whenever possible, this is fine by me. Unfortunately, they didn't do a great job of making the UI/menus as intuitive on keyboard.
Anyway, I added FloydTheBarber to my friends list!

I think you'll have to add me on your end if you wanna see me online. I'm maining TheWard for the moment. I made him earlier. He's already level eight. haha
I used to write guides for this game. The two like... non-forum-post pieces I found are mostly suited for that point in time just after hitting the level cap and beginning to move onto PvP and alerts/raids. If the shameless self-promotion doesn't bother you, here're the tidbits I shared about
gearing up and
hitting harder.
If you, or anyone else, has questions, there's a good chance I have answers. I really like this game, and I've put way more time into research regarding it than any other game. I've even put more time into it than I've put into Street Fighter theory.
...now you've gone and gotten me all excited about the game again. I wanna write more guides, this time catering more to entry-level stuff. haha