Once the male catches the female he will wrap his body around the female and attempt fertilization.
This may take a few attempts as the male sometimes drops the female.
As the female starts to drop eggs the male will catch them and place them in his nest.
Sometimes the females may try to eat the eggs. If you notice this, just remove her.
However, it is important to note that females can also help with placing the eggs in the nest. Be sure you are aware of what is actually going on before you remove the female.
If the female is not interested in the male betta, they may destroy the bubble nest. If this happens, remove the female, let the male build another nest and reintroduce the pair.
If the female destroys it a second time, you may need to find a new breeding pair.
Watch this short video which gives an excellent overview of the Betta fish breeding process.