Can you give some more information? What did the things in her tummy feel like, how long have they been moving, ect.
If you're positive she's pregnant then yes you need to make her nesting boxes, preferably two or three to choose from, in darker, quiet areas where she can be by herself. Set her up a litterbox and food/water near the boxes so she doesn't feel that her resources are far away. Monitor her movements and behavior and read up on the signs of labor so you can be prepared, also start feeding her kitten food bc it's good for her and the babies.
These articles should help answer some of your questions. There are more pregnancy and kitten articles at the top of this forum. Keep using this thread for your questions.
[article="31379"]Pregnant Cat What To Prepare For The Birth [/article][article="29720"]Pregnancy And Delivery In Cats [/article][article="31414"]Help My Cat Is Having Kittens [/article]