Jack:
I use Photobucket to upload my photographs. Once you upload a photo to Photobucket from your computer, the "Edit" tab permits you to downsize the image to dimensions that fit the Forum's software. Something around 490 X 367works pretty well. Photobucket offers a free service for a limited number of photos, and I have found the cost of unlimited hosting to be very reasonable.
I hope all of that is of some help.