Product Photo Sizes

I’m in the process of creating product pages for my charity auction. It’s taking me forever because I’m totally new to building websites, etc. I initially uploaded photos for the product several weeks ago. Everything was fine.

Then I recently tried to add a new product with photos. The main display photo grid is fine, but when I try to click on the product photo to enlarge it, the enlarged photo is HUGE and doesn’t match my original product photo sizes (this sample here is what I need).

I’ve tried adjusting file sizes, but it’s not working. How can I shrink the “enlarged photo display”?

The page I need help with: [log in to see the link]