meh. I would scold you for not reading up before spawning them :p hehe but that's ok ;) The eggs will hatch in approximately 2 days, with their tails hanging down. during this stage, they are still feeding off their yolk sacs and you do not necessarily need to put food in the tank. You have to observe them during this period, until they can swim horizontally. In my case, I remove the male at the first sight of a free-swimming fry. The others will soon follow after they are done with their yolk sacs. It is important to feed them immediately after you see them free-swimming, even if they are only 5 or less at that time. If you wait until all of them are horizontal, chances are that the first batch of free-swimming fry will be starved already.
What to feed them? Live food will always be the best, the wriggling or movement of the food will stimulate their natural instinct to eat it. As in nature they will eat anything that moves and can fit inside their mouth :) So by now you should already have a thriving culture of microworms, infusoria etc. You could also hatch BBS(baby brine shrimp). But don't fret if you don't have them yet. There are alternatives, like boiled egg yolk or Atison's Betta starter. In feeding boiled egg yolk, you pinch off a SMALL piece and run it through a fine cloth and dip it in the water. On the other hand, Atison's Betta starter is readily available on the net. Make sure to not overfeed, especially with the alternatives, as they spoil the water rather quickly :(
It would be best if you read up on it more, this site offers a great deal of information to help beginners like you :D
We're here to help ;)