How to take care of a baby bird?

On a walk my mother found two baby birds that may have fallen out of a tree. One was already dead but the other was still alive. We have the bird now to just help it hopefully get better and not be out in this heat. What can we do/feed this bird, what type of living conditions should this poor little bird be in, heat lamp? She is at the stage where she is waddling around and her eyes have not yet open she’s about the size of a large strawberry. Thank you for all the help this little guy needs it!