Theres lots of poeple ten times more expirenced than me but I can tell you what I know.
After they mated and the female finishes relaseing the eggs you take her out and the rest is up to the father. I dont remember how long until the eggs hatch in the bubble nest someone else will probably tell you but I believe its after 3 days when they hatch you take the father out (which should be around when they start swimming freely) otherwise the father will eat them. Have a lot of hidding spots for the female that way when it is time for them to mate if she needs to get away from the male to rest she will be able to. Last thing you want to do is stress her out! There is a forum on here that you can read for yourself but she was able to breed 70 fry! So they can have lots of fry at one time. Make sure to have plenty of space

That's really all that I know when it comes to breeding.
I have some plants that reach the top towards the corners of my tank that way if my male wanted to he could build a bubble nest under the leaves (some like to do that). When first introduceing the female to the male make sure you put the female in a clear container where he can see her. I normally leave mine in over night (night for me is only 4-6 hours since I dont sleep much. Im a night owl lol) Then if the male is flareing a lot and charging at her I would normally give him a break so he doesnt make himself sore with all the flareing. I have had one time where one of my males instantlly made a bubble nest after seeing her so I was able to relase the female right afterwards but that doesnt always happen.
As for the fry, lots of people feed them baby brine shrimp, other use cooked egg yoak (although that makes the tank really dirty) but there are other things to feed them as well that I do not remember the name of... someone will probably mention it. Not sure about putting them in their own cup, I always kept mine together until they started showing colors unless they started showing aggressive behavior at a younger age.
Wait for other people to respond as well, they will probably have a lot more information for you, I have only been able to breed bettas twice. Once with my 8th grade teacher (5 years ago) and once last year on my own. So they should be able to help you a lot more than I could.
