I would have to say that I take the smart way out and DON'T breed bettas. First of all do you have 1) a breeding tank of at least 10 gallons seperate from the one you have the fish in now; 2) a hospital/recuperation tank for the female after spawning (at least 5 gallons); 3) a 55 gallon tank to allow the room for the little females to grow up until they are ready to be sold/given away; 4) bunches of small containers for the male fry to go into when it becomes obvious that they are male so they won't kill each other. All of these have to be fully cycled and of the cleanest character AT ALL TIMES, including all the small containers or the fry will be deformed and the fins will not form normally. This means DAILY water changes of at least 50% on ALL of the containers and constant water testing. You also have to have good temperature control through all this. Now I do not know how the professionals take care of heating all those little containers, but I do know you cannot just let the room temperature do the job as there would be too much fluctuation. Now, please do not give me the argument that they are kept in the petstores in unheated containers. Those are not fry they are grown fish. Fry are still forming fins and bodies and have to have PERFECT water/temperature conditions to develop into beautiful fish. To breed bettas takes MUCH work and more EXPENSIVE equipment. Unless you are planning on opening and running an operation to do this as a profession or you are independently wealthy and can afford to buy anything you need and hire help, I wouldn't consider it if I were you.
One other bit of information, I am not saying all but MOST of the Bettas sold in petstores are past breeding age and even if you introduced them they would probably not spawn. What ever you do though DO NOT just put a female into the tank with a male. Getting them ready to breed means a special diet and conditions for days or weeks ahead of time. I would suggest that if you do not know how to do it yet and are determined to continue that you HURRY to the public library and get the biggest book you can find all about what you need to do to get them ready to breed and read it thoroughly. You may do what you will but I am totally against amateurs breeding one of the most difficult fish there must be to get set up to breed. One more thing, there is a very real possibility of losing or injuring one or both of your breeding pair if you do introduce them at the wrong time and they are not ready to "be nice". They can and will hurt each other.
Rose