Shotguns are pretty easy to clean and take down, field or detailed. If you don't have an owner's manual, I'd recommend a search on Youtube. There's usually several good videos of disassembly & cleaning/maintenance, as well as various websites.
Make sure its unloaded.
There are many different opinions here on how often you should clean it and what you should use. I find that cleaning supplies are like oil for your car or motorcycle - everyone has an opinion on why what they use is the best, so you will likely have to develop your own opinion in that regard on what works for you, and what you like.
For me, I clean my guns after every time I use them. Could be because I'm ex-military, and that was drilled into my head, or the fact that I'm also OCD, I don't know. I like my weapons always to be ready, and like-new at all times.
I use nitro solvent to clean, and a brush, followed by gun oil after with the usual rags you get with any cleaning kit - Hoppe's is what I use, but I'm sure there's a ton out there.
Good luck, and be safe.
Cannon