So here's the deal (or at least the deal w/ what I know hehe) -
You'll need 3 places to keep your bettas if you plan to breed them. One for the male, one for the female, and one for them to be together in - breed in, and then eventually remove them but leave the fry.
The male will build a bubble nest when he's ready to spawn (in the roots of a floating plant at the surface of the water), this is where the female lays her eggs. The male will display very bright colors when he is ready to breed, and the female will often get dark stripes. After the nest is built, introduce the female and if she's ready, the male will "flirt" by flaring up, and sometimes some nipping. Eventually he'll curl around the female and squeeze her eggs out, which float to the nest.
After spawning is complete, the female should be removed but the male left to guard the nest for 3-4 days. After the fry hatch and are free swimming, the male should be removed.
There are certain things you can do to condition a breeding pair, such as feeding live foods (ie: brine shrimp) and keeping the water temp around 80. Check other posts and places on the web to find out more. Hope this helps!
Also - spawning can take anywhere from 1 - 24 hours, but if it hasn't happened by then or the male is harrassing the female, seperate them and try again another time. If you're careful and know your fish, you shouldn't have any problems, and the male will not kill the female. If this happened, how would we ever have betta babies!!