If you want to use a commercial picture it will have to be from a site that allows linking. There are many of them out there, most free, and you might just try a google search for something.
If you want to use a personal photo of some kind, such as your family at WDW, then you'll have to have a place you can download the photo onto. Most ISP's provide personal web space for their customers for those wanting to have pictures or to have a personal web site.