If you want to look for allies, click on the Allies button and then search for allies. if you want to find someone specific, click on trade then enter user id, and click search. you can then request ally from their wall.
BTW, if you haven't done so already, read the stickies at the top of the forum threads - lots of good advice and will answer a few questions you haven't thought of yet.
I would offer to ally and give assistance but I am out of rookie slots at the moment (keep 10 for rookies and 20 for solid allies). Anyway, good luck with the game and you will find some awesome people on these forums to ally with