Want to go on a cruise.

I've nver been on a cruise but I want to take my mom for her birthday next year! We live in Texas so we prefer to drive to the loading area in Texas to go to Mexico. Where should I look to do the booking? Is carnival a good one to go on?

I dont know much other than you get on a ship and you can get off at some stops and get back on. Any information is appropriated! Thanks