Hello

You need to keep baby chicks in the brooder until they are fully feathered. I use a large plastic tote and a heat lamp for just a few! Make sure they can get away from the heat lamp but it's not too far away at the same time.
Make sure they have fresh food and water, and that they are away from other pets. Cats, dogs, ferrets, etc. love chicks, for a different reason than you do.
If you're feeding them anything other than chick feed, they will need chick grit. I just use sand from the stream in my yard, but not everyone has sand so readily so you may have to buy some chick grit.
Then it's best (once they are feathered) to move them to a pen (separate from any adults). I have a small 3x7 cage for them to spend their few months until their ready for the flock!
The learning center is a great place to find information and tips on raising your flock
Good luck
*I just realized this was in meat birds, silly me xD
Like chick charm stated, most people remove food for 12 hours because Cornish X grow very fast. My knowledge on them is limited but I would love to get some soon to try