Good for you! I'm a huge proponent of keeping cats indoors. Both of my cats were outdoor-turned-to-indoor - one was 3, the other was 14 when they became indoor only cats.
This is a great opportunity to establish playtime and love time! There are tons of toys you can try to see what your cat likes. My Sammy used to love it when we played with a little plastic ball with catnip and holes for the catnip to come out! I would roll it, he would chase it . . . He also liked the fishing-pole type toys. My cat Bodi preferred stuffed catnip toys and would amuse herself. I would retrieve them from under furniture for her.
I spent lots of time with both Sammy and Bodi on my lap or next to me on the couch petting them or brushing them. I had a different routine - established by the cat, natch - for each cat, but we spent quality love time every day!
If your cat has claws, it's a good time to figure out what kind of scratching pad or post she may like. Both of my cats preferred the disposable corrugated cardboard kind. I would make sure there was fresh catnip on it once a week or so for them to roll around in after scratching.