Hi first time cruiser jen, welcome to Cruise-Chat! Congratulations on your upcoming cruise. Take a look in our FAQ section at the bottom of the main page, most of your questions are answered there. I think your ports are Cozumel and Progresso? Cozumel is very doable on your own. You can grab a cab and go to Chankanaab Park or Paradise Beach. There is an entrance fee to Chankanaab, $19/pp. There is no fee at Paradise, but you can buy a package for various activities, chairs, etc. I prefer Chankanaab because the snorkeling is better, but I like snorkeling. Progresso, either take a ship's excursion or just go to the beach.
Hope you have a wonderful cruise!