My cat is throwing up white foam. Help?

Well im not a vet or anything but my cats do that some times and that's when there in the house to long. Your cat might just have a stomach ache from eating wet food. Cats will usually eat lawn gr to cure there upset stomach. So maybe go and get some gr for her.or you can go out side with her and let her walk around outside and let her munch o n some gr. Hope i helped good luck!!(-: