If you want to breed two of your own Kitties together, go to your litter and click on a Kitty you want to make the father (the Sire) in your breeding. This cat will show a “Breed” button. Click on that, then click on “Sire with my Kitties”. After that, you get to choose the Dame (or, the mother) for your breeding. Once you’ve selected a breeding pair, hit “OK, give them some privacy” to open a transaction window and let those Kitties make some magic.