Thank you! I tried looking up Photoshop compression on the internet (and in their help), but none of it seems very simple.
It's been quite some time since I tried to use Photoshop, but if I remember right, if you're saving as a .JPG, there is a "quality" slider in the "Save" dialog that basically controls the compression level of the JPG. It can make the image "fuzzier," but typically it's less noticeable in small images.
(trots off to check the wife's computer)
Yep, after you choose the file name, a dialog box comes up with quality options. Lower quality = higher compression.