After I crop my photo, how do I SAVE the edited photo?

If, by "save" you mean save the edited version of the photo to a folder (or the Desktop) on your computer, you choose File > Export (CMD-SHFT-E). Don't choose "Export Unmodified Original", because you'll loose your crop and other edits.

If, by "save" you mean send the edited version of the photo to someone, there are lots of options under File > Share.

Good luck :-)

Photos saves the edited image without the user having to click 'save'. It also, by the way, keeps the original unedited version around in case you want to revert. That's how it works on my iMac, hope it's the same on yours. Good luck.