The way how I get my profile picture to show is an automatic thing. I just signed up (free) with http://en.gravatar.com/. You upload a picture and register an email address with them. Then this profile pix will automatically show up whenever you post in any online forum as long as you list the email address which is on file with gravatar.

The second method is to edit your forum user profile section. Click on the "edit avatar" tab, and then you can upload an image from your computer.