You have have a look at the instructions here
http://www.3fatchicks.com/forum/forumdisplay.php?f=40
Everything I've learned, I kinda guessed and found my way ....
You can just look at the main forum board ... like when you click on 3 Fat Chicks on a Diet Weight Loss Community at the top of this page. Read and click on any thread you think looks interesting.
You can click on 'new posts' in the purple bar at the top and see all the threads that have been active since you were here last.
You can find someone you like and click on their name in the box to the left of their post. You be able to get at all their posts.
As for stats ... you can get to your 'user cp' in the purple bar at the top of the page and edit your profile. Once you've been here for a while, you'll be able to add a signature and weight or exercise tracker.
So far you're doing just fine. Ask away!