Hey, I saw that you needed help for userboxes. If you find the picture you want on the wiki, click on it. For example, if you go to Gallery:Elizabeth Gillies and you want the picture "Keep Calm and Love Liz Gillies" that you uploaded. If you click on it, you'll see the file name File:Liz_gillies_love.png. Liz_gillies_love.png is the file name you want to put where it says NAME OF FILE in the userbox tutorial's code.
Hope that's what you needed, but let me know if you have questions about it. :]