the pic shall not be too big...
and you have to look on if its an internet file or just a file on your pc.
if its an internet file already, in other words: if you have a link, then fill in the link where it asks you for a link
if that picture is still on your comp, and not available as a link, you need to upload it. then it will ask you to search a pic from your pc. the smaller it is, the less problems you will have putting it up.