Electronic music in the virtual world
First you need to be logged in to the website. Once you're logged in, you'll see some options on the right of the web page, underneath where it says your name.
Click on "Settings" and you'll go to the "My Settings" page were you can update anything to do with your account.
Click on "Browse" to choose an image on your computer you'd like to use as your profile picture. The image you choose won't always be displayed as a small icon, so you can pick something reasonably sized.