I love the color, and the waves!  HI!

There is indeed a way to add it to your avatar.

open up your profile, and click the little button that says modify, it should be in that top, purple section, over on the right side.

Confirm your password, and then click the tab that says options. (or you can just click the change profile button on the bottom, and then again when the new page comes up) then where it says, 'I have my own pic', enter the URL of your photo!

Hope that helps, and Welcome to LL!