Hi and welcome to WOL
Log in,
In the upper right side of screen you will see your user name, and the words "My Profile"
Click on that,
It opens up your profile page.
On the left side there is a small pencil looking icon next to the words "Friends"
Click that little pencil icon.
This will open the page to add or delete friends. It also unlocks the secret access to "My Settings" found on left side of page. (Eddie does it that way to keep out riff-raff) :dont_tell:
Click Edit Avatar and it will open the dialog box to add your avatar profile photo. You can load it from a web page or right from your computer.
Sorry I cant remember the size limits.