You've probably noticed that your nicname is underlined in the left side column when you post. Simply click that to bring up your profile page. You can also view another's profile in the same way. Once the page is up, you'll see a menu of assorted goodies you can use. 'HOME' will bring you back to the board listings. One of the selections is "Avatar'. An avatar is simply a small image or gif you use to represent you. First the image must be on your hard drive. Simply follow the prompts to upload it to your profile. Also from this area you can edit your profile, write your biography, change settings, or order up a digest! You can even send PRIVATE messages to others in the community! Or you can go to someone's 'white board' on their profile and leave a message! Amazing!
Or you can go to someone's 'white board' on their profile and leave a message! 
