i was wanting to get one for a class called "Aquatic science & geology" in my junior year. i figured few people have them (or even heard of them) and would be different than wat the other kids have. i already have a bullsnake and i have love reptiles since i was little, so im not a total noob to reptile care. i was just wondering how the heck do they breathe? do they have gills?

They do not have gills.
Just like sea snakes, they come to the surface periodically to take a breath.

They come up to get air.