Leave her alone. Neither Tito or Sophie were much interested in eating when I first brought them home. And neither one of them used the litterbox for the first two days.

Cats take a while to adjust. Let her hide too. Forcing her to come out from under a "safe" spot like a chair or bed will only make her defensive. Set some food out and fresh water. Most likely, she'll eat it tonight while you're asleep.

How's Tigger doing with all this? Has new kitty got her shots/deworming yet?