BEFORE breeding your bettas, you need to have an idea of what you are going to do with up to 200+ fry because that is a very normal number for a betta spawn. You need a tank for spawning your bettas in that is cycled, heated, has a couple of plants, and is around 10 gallons(38L). You will need quality food for your pair to condition them for the spawning and small live foods for the fry when they become free swimming, Betta fry do not normally do well on foods that are not alive. You also need jars/containers for the betta fry for when they start showing aggression to each other -- usually as early as 2 months old. A good start is 50 of these containers.
Once you have these things, then you can start to condition your pair. Conditioning is the process is feeding your pair of bettas really good food (I prefer live/frozen) twice a day for two weeks to help them prepare for spawning. This will help the female produce good eggs and the male be healthy and in good shape to take care of the eggs and fry for 3 days or so until they become free swimming since he doesn't eat during that time (normally). It is best to condition the male and female bettas separately in tanks next to each other with a piece of paper blocking the site of the other. It is easiest to already have the male in the spawning tank. During the second week of conditioning it is good to remove the paper so they can see each other for a little while each day to help with the conditioning. At the end of the two weeks, adding the female into the tank via a chimney(or anything that the female can stay in without actually being loose in the tank will work) will let her and the male see each other and start the courting process. The male will flare and show off for the female and will start to build a bubblenest. The female will normally dance for the male, show vertical stripes, and be nice and full of eggs. Once you see most of these signs, you can release the female into the spawning tank. It is important to watch the pair carefully. Some aggressive fin nipping is to be expected but one or the other totally beating up the other is not a good sign and the female will need to be removed as soon as possible. If after 3 days there are no signs of spawning, it is advised to remove the female because keeping them together any longer is asking for one or the other of your pair to get hurt. If the pair actually spawns, they will go under the bubblenest and the male will wrap his body around the female which expells the eggs. The male will then pick them up and spit them into the bubblenest and this will continue until the spawning is complete. Once spawning is complete, remove the female. The male will be very protective of his nest and that becomes dangerous for the female. Plus the female will eat eggs. The male will continue to put the eggs back in the nest until they hatch and then keep the little fry in the nest until they are free swimming horizontally (normally on the 3rd day). At this point it is good to pull the male out so that he can have a rest and good feeding.