Hi Princess Pris and welcome to The Royal Forums! I hope you'll enjoy it here.
At the top the page you find a blue bar with 'User CP' as the first option from the left. Click there und the next page will show you 'Your Control Panel' on the left. In this panel the third option from the top is 'Edit Profile Picture'. If you click there the next page will give you the choice between entering the URL of the image, or to upload the image from your computer.
I hope this helped
. If you still have problems, please let us know where at which point it does not work for you.