I've always found it quite tricky, I gave up trying to rescue my fry as they always died. The problem is that the fry need constantly warm humid air above the water until the labyrinth organ had grown If you can supply this, you have more chance than me of raising the fry.
At first, feed infusoria or liquifry for egg layers. This works best if you add the drops to a container of water, mix it then add to the tank. If you put the drops straight in, they'll just fall to the bottom in a clump. As the fry grow, they can be moved on to baby brine shrimp.
Rather than go into detail here, google culturing infusoria and baby brine shrimp
