It is a long process that involves a few WEEKS of special foods and conditioning to prepare betta splendens to have the stamina for breeding and then you need to have the equipment a partial list I will put below. The cost will run you into the hundreds if not thousands of dollars for the set up and you will need to set aside a special room for the equipment and all the stuff as you will need to have it temperature controlled to the bettas specifications to keep all the jars at the temperature you need for the male fry as the jars cannot be heated. (100s of them). Then you need to be sure you will be available and present during the whole spawning so that when they are finished that they do not injure or kill each other or tear the nest apart with their fighting. Then you will need to put them in seperate tanks (the male stays with the fry until they can go freeswimming) to recuperate (many of the males die from exhaustion from caring for the eggs). The female will need to recuperate from her ordeal in a tank alone also. She cannot be put back into a community tank to recuperate. Then after you have the parents out of the breeding tank you have to start to watch the fry and every day they will need a 50%
water change (carefully so as not to throw out the babies with the bath water). When they start to show which are males you have to seperate each male into his own container (jar) and then the real fun begins. Every day each and every jar and tank has to have a 50% water change to allow them to form their bodies and fins without becoming deformed from
nitrite or
nitrate or
ammonia buildup in their water. Remember that none of these containers is filtered and cycled. You do this for about 3 months on a daily basis or until they are big enough to go to other people and believe me this is not a money making deal. The market is overloaded with people selling bettas and the chance of you having any bettas that you would be able to sell for a profit is nearly nil. Remember the professionals are out there competing with you and they are willing to sell cheap and they already have their initial investment costs back. They also have a staff of people who assist with the work.
Here is a PARTIAL list of what you will need:
Breeding tank of at least 10 gallons in size
Recuperation tanks for parents of at least 5 gallons in size
Growth tank for fry will eventually hold female fry to 3 months at least 55 gallons in size
about 150 to 200 jars about 1/2 gallon in size for the male fry to grow in
Dechlorinator for water changes (better plan on buying by the gallon)
Some way to grow and hatch Baby
brine shrimp for feeding fry as this is what they will eat
Special area that can be kept at 80 degrees to maintain temperature in jars.
Frozen foods (high protein for parents to condition them prior to spawning)
All the equipment to go along with the above tanks and if possible it would be lovely to have an aeration system of some type for the jars. This would amount to a LOT of airline tubing, airstones, and airpumps. Several jars could go on the same airpump but it would still amount to a lot of work to make it work.
This is only a very short description and a very abbreviated list of things so while I know there are people who do it, believe me, it is really my opinion that this is something best left to the professionals. If you are really wanting to do it then go into it with your eyes wide open. It is going to be expensive, time consuming and a lot of very hard work and you do run the real risk of losing one or both of your fish.
Rose
Similar Aquarium Fish Forum Threads 
i had a great teacher!!! 
your very much appreciated!