The direct link to the image ends in an image format, such as .jpg, .png, .bmp.

Here is how...

Go to imagecoast.com it is site that you can use to host your pictures.
Once you upload a picture to the site you will see a box that says url
Cut and paste the url from the picture go to ter to the picture url box clear the http:// out of the box.
Paste the picture url from imagecoast in the ter picture url box and your picture will show up in your ads.
Good luck to you.