Are there any wildlife experts or vets out there that can help me?

I'm the one who wrote in yesterday asking for help with abandoned sparrows. Well, I got the nest down today and there were five babies , four of them which were old enough to fly away. But there was a little one who could fly only on the ground. He's too young to fly in the air yet. I'm feeding him moist kitty food like "bobbi f" said to do. I just want to know how often I have to feed it and how long it will be before it can actually fly away. I fed it a little bit and it ate. I hope he survives. I saved the nest and put him in it and put it in my cat carrier because I don't have a cage and I don't want my cats to bother it. What else should I do?