Hi....I am way way older than 13 and this is my very first time with baby chicks too. So my help will be kinda limited. I would suggest you go to the library and get as many books as you can on raising chickens. There are hundreds and hundreds. If you can't get to the library, do a search on line and read all you can about it. This web site has the best info I have found and the book Raising Chickens for Dummies is pretty good to.
You will need a brooder box of some kind....with only 3 chicks you can probably use a deep rubbermaid container, a large cardboard box, something that will hold them until they go into the coop. I have 11 chicks, and I got a large deck box that I plan to use later to store their feed and supplies in. I lined it with heavy vinyl and use baled bedding I got at the farm and garden store. It is like thin wood chips. The only restriction I remember is not to use cedar.... I also got a feeder and a waterer that I just place in the box with the wood shavings. They are messy and grow pretty fast so get something that will hold them until they go out into a coop...that way you are not having to "up grade" their housing for more expense. They will eat a chick starter food and according to the farm and garden store (I also got the chicks there) they will eat this for 16 weeks. You can get small bags which is what you would need for 3 chicks. If you have a
tractor supply near your house they have all the stuff you need at pretty good prices. By using the wood chips, and only 3 chicks, you should be able to go a few days between cleanings. Mine are only a week and 2 days old, and they are really "poopy" and get it everywhere. I use a pretty deep layer of bedding and stir it around daily. I can tell, it is going to need to be changed at a minimum of every other day as they grow. I also keep mine on my screened front porch, less mess in the house, and with a heat lamp and cover for the box, they are keeping plenty warm.
I hope I have helped you some and if you have other questions, just post and I will answer when I can. Will be offline for the next 4 days though.
Good luck and maybe we can learn this chicken raising business together.
Murphy