Firstly put some eggs under the broody now so she believes she will hatch chicks. Give her some time on the eggs - closer to 21 days the better. Then order your chicks. The chicks need to be less than a week old (ideally under 3 days). Place them under her wing at night while she can not see what you are doing. Don't let her see the chicks - let her think they hatched under her. As you put a chick under her wing - watch. As the chick tries to get comfortable/runs out from under her, she should gently pull it back in under her. Continue then with next chick and so on. Take the eggs from under her at this time also. Then just watch for a little while to make sure everyone settles for the night.
You will need to have unmedicated chick starter for the little ones, Mama, and the rest of the flock (provide oyster grit also for the laying adults) if you are not separating the hen and chicks. It doesn't always go so well having chicks with the flock so watch carefully. If you had somewhere separate for Mama and chicks that may be best.