Hi, Jim. I'm not sure which picture folder you mean, but to add pictures to your registry, under the "Registry" tab, choose "My Trailers". Once there, click on "Edit" and you should see several "add images" options beneath the pic(s) you have already uploaded to the registry. I'm afraid you must upload any images one at a time; locating the picture folder is, I guess, the answer to your question: is it a folder on your computer?
I hope this helps, but I'm afraid it's inadequate.