How to care for baby finch?

I found a baby finch that has fallen out of the nest because of last nights storm. It appears to be almost fully feathered with a few pin feathers here and there. It was trying to climb the tree to get back to its nest but the storm has shredded it. I put it in a small cage with gres and water but its staying in the corner of the cage. what do i need to do to keep it healthy until it can fly again?