I'm not 100% sure where you want the image to go, but something like this:
Code:
#profile_photo_galleries:before {
content:url('http://f.mfcimg.com/photos2/138/13812921/980-368-183-211-7386209.jpg');
}
... in the Customize Profile section, will insert an image from your MFC Photos (in this case, a simple "Test" image) immediately prior to the Photo Galleries section.
Obviously you'll have to load a suitable image somewhere, such as one of your MFC photo galleries, and get the URL for it. You can use other CSS selectors to move the image around in your profile, and also position the image with a greater degree of control, if you hunt through some guides on using CSS. Explaining all of that, is somewhat beyond a single post here!
If you make sure that the image is the size that you wish it to appear in the profile, then you will not need to do anything else, but you can also resize how it appears using CSS, if necessary.