How do I make friends? Is there somewhere I can go to find people to send requests?

In the achievement forum there is a thread called something like "a friend in me" and you can post there to add friends for the friends achievement. These aren't "real" friends, its just to quickly accumulate people for for achievements.

As for making real friends, that takes a little more time and effort. You can post a topic in the welcome forum. You can look around the general forum for interesting topics to post in. You can look in the bragging forum and congratulate/commiserate with people. Then you can check out the Forum Groups forum, here you can look for groups that share your interests and join in on conversations and stuff.