I'm not the best at this but here goes.This only works for a picture somewhere on the net. Not one in your PC. If you want to use one in your PC you have to upload it to the net using an image host site.
Then, follow these directions from there.
1) Right click on the pic you like.
2) Select 'properties'.
3) When the properties window pops up, Highlight with cursor the URL.
4) Hit Ctrl-C. (copy) It's now copied to memory.
5) Go to LionBacker Profile screen. Find 'Link to off-site Avatar:' (at the bottom).
6) Click cursor in that box.
7) Hit Ctrl-V. (paste) It's now pasted in there.
8 ) Click on Submit.