Madeguada- My cat Liza (10 years ago) had 5 kittens. She was a stray who was preggers when we got her.
I made up a box for her in a spare room to keep our other cat and 2 dogs away from her and her babies. She seemed to just LOVE this box.
The day her kittens were born, she decided to have them somewhere else: we had an old sofa with a sheet over it in that room, and she went under this sheet. When I came home, I could tell she had had her kittens, but could not find them for awhile. You could not tell there was anything under there at all, since the sheet did not look disturbed at all.
I looked all over the house and found nothing. I was getting SCARED. Finally I thought to look there, and there were 5 little kittens!
I moved them back to the box, and she moved them back. This happened about 3-4 times. I eventually figured out that she liked the 'cover' up there, so I made a small one for her box.
She was happy then.

One thing the vet told me to do was to set-up her box quite awhile before she had her kittens so that she gets used to it.

Good luck to you and your new family!