Once in captivity, it is actually illegal (in my state anyway) to re-release them into the wild due to the risk of introducing foreign environmental contaminants. And it's illegal to begin with, to collect them, unless you have a fishing license.
We have raised tads in the past few years; had some eggs that were in a drying-up puddle that would have died anyway. They go through a transformation (of course!) from eating plant life, to insects; for the ones that are still tadpoley, you can feed them crumpled fish flake food; I actually like to try and get some of the plants and water they were living in, to kind of wean them off of that and get them onto the flake food.
Hopefully for you they are not bullfrogs! One alone is cramped even in a large 125g tank. We raised ome from a tadpole and ended up letting her go at a local nature preserve's display pond.