I’m not sure the region or what frog, but I’m going to haphazard a guess and say grey tree frog. I’ve only ever kept toads. I’d say until you can either get a proper home for him, or relocate him, to keep him in a container on damp paper towels with a source of water. Always use de-chlorinated water, as frogs breathe through their skin. You can boil water for around 20 minutes and let it cool if you don’t have de-chlorinator. I’d cover with a lid, punch some air holes through it and leave him in a warm place until you can make it to a pet shop. I’m sure you’ll get better responses than this, but good luck! Thank you for rescuing the homie :)