Next, just relax. Most likely, the Momma cat knows what she is doing. Mostly you just are standing by in case of difficulty, and then you call the vet. Keep kitty quiet, don't let the kids and neighbors in while the birth is going on. She needs peace and quiet, and a warm nest to keep her babies. Make sure she has food and water nearby, and a litterbox nearby. Often, new Moms don't want to get too far from the babies.
Soon, many more experinced people will be posting. Best of luck with the babies. Congrats!