My Sunshine had a litter last August. We set her up in a laundry basket well before hand w/ towels and blankets. When the "moment" came we immediately knew. She was hiding under a table and panting really heavily. We put her into her basket and put her in our bedroom where it was pretty dark.
She labored for about an hour or so and then started meowing and pushing. She delivered the first kitten in about 10 minutes, then the others all came about one every 20 minutes. She had a total of 5.
As far as what to do, do nothing at all if she is fine. She will clean them and eat all the afterbirth herself. She was fine, she even let me stay in there with her while she did her " duties" and let me pet her and soothe her. I called the vet once it was over, and they said to let her be, and the kittens would just nurse on their own. I did read if she appears to be in trouble ( like its taking her a long time to deliver, and maybe one is stuck ) then you should be able to at least call a vet or go to an animal ER.
Sunshine kept her kittens in the basket for about 2 weeks. Then we moved her and them into a large playpen, in the same room. It worked out great, Sunshine could still get out but the kittens couldn't. Yet they had room to move about a bit. WE kept blankets in there for them, and made sure it was clean. We didn't handle them too much, so our scent wouldn't interfere. When she needed to roam a bit she was able to, but she was basically confined to that one room. Sunshine did great, she was a great mommy kitty. Hopefully you'll be as lucky as I was.
As the kittens got more mobile and older ( 4 weeks or so ) we started giving them so wet food in the playpen and then introduced them to a litter box. By 7 or 8 weeks, they were able to climb out so we let them out. They were slowly introduced to the rest of the house and did wonderfully. We kept them till 12 weeks when most of them went to a good home. Oh, by the way, did have them vet checked at about 3 weeks to just make sure they were ok
If at any time you feel something is wrong, just call your vet!! I was nervous, and it all turned out fine. Just trust your instinct, especially once the kittens arrive. If they seem sick in any way then don't hesitate to post here or call the animal ER.
Enjoy your new found family!!!