Hello and welcome to FF! Not a tree frog; looks like a juvenile Rana clamitans, commonly known as a Green Frog. Can be kept as pet, but check with your state's fish and wildlife webpage to ensure it's legal to capture.

Can set-up a tank for it following this care sheet for Leopard frog (similar requirements): Frog Forum - Leopard Frog Care - Rana pipiens (Schreber, 1782) and R. sphenocephala (1886) . Also, here is some information on their natural habitats: AmphibiaWeb - Rana clamitans . Let us know if keeping it and good luck !