What to do with baby Zebra Finch?

Hi A baby zebra finch has just hatched (other eggs were infertile) and whenever it is in the nest it keeps falling out because the parents push it out i don't know if it is on purpose or by accident but whenever it's returned to the nest it always falls out and sometimes it's really hard to find when it falls and im scared it will die. So i decided to put it in a small pets plastic container with layers of tissue and sometimes warm it up with a lamp. Any tips on how and what to feed it?