Did you try this?
If not, just copy and paste it, then change where it says URL to the url of the image you want.
I don't know if you're using image tags to put your stuff on your pages, but this should work I think. And I'm also not sure of what you mean by 'behind' the picture, so I'm going to guess you mean after, like you want you're thing to look like this:
blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah
(also the padding=5px thing can be taken out if you want, it just makes it so that the letters don't get too close to your image.)
