For the forum option, you can either go to the User CP, click on Contacts and Friends (under Networking on your left), and go to "add a member to your list...".
OR, you can click on the profile of the member you want to friend, look on the right hand side for their friends list, and there should be a little link that says "Befriend [member]". That also works.
If you mean make friends in general, well... talk to people. 8D
