Thanks to both of you for the quick responses.

The person at Autozone said the code was P0455, evaporation emission system leak. The manager then came over and asked if I had opened and closed the gas cap and if the blue plastic around the gas cap was at all damaged. I went out and opened and closed it again, and no, the blue plastic was in perfect condition. I still had the check engine light on, so the manager told me I should purchase a new gas cap, Duralast Fuel Cap item 6842. Should I do that?

For the scanner, is this the one you're talking about:
https://smile.amazon.com/gp/product/...D1JAFECP&psc=1

I really appreciate the assistance here. I can change a tire and my windshield wipers, but my mechanical skills aren't much beyond that!