After many frustrating failures, I've figured out why my photos don't enlarge when you click on them like they do on other people's blogs -
I've been saving all my photo files as ~16x12 size... roughly 200 - 300kb each... because I want them to fill your screen when you click on them but it hasn't been working and now I know why!
When you upload photos, they go to the top of the editing window and I usually write the text first so I've been using the "drag and drop" feature in the editor to put my pictures where I want them in the post and that sometimes breaks the link to the photo somehow - the trick is to use the "Edit Html" mode and cut/paste the whole block of picturecode rather than just dragging the photo in "Compose" mode. This is a lot harder because you can't really see what you're doing... but it's worth it for my readers ;-)
Example - the same photo, uploaded twice: The top one was dragged in the compose mode, and the bottom one was cut and paste from the html mode.
I'm going to have to get good at this to help justify the expense for a better camera, but from now on, click away people!