Speaking from breeding experience, you should set up the male, solo, in the breeding tank at least 3-4 days before you introduce the female. The tank
(I used a bare 10-gallon for my setups) should be completely bare. No gravel or anything other than a submersible water heater, a bit of java moss(optional) and either a fake plant who's limbs reach the water's surface or a favorite of mine was using a half of a plastic cup (the colored ones are easier for the male to see and build under) immersed just enough so that the edges are 1 cm below the waters surface (I secured it with waterproof electric tape. You'll also want to sink a clear beta cube or hexagon... or a clear jar into the center of the tank.
The best depth of water would be 4 inches and I always treated my water with conditioning solution and a tsp of blackwater extract. Helps the fish to feel more 'natural' and they breed easier. It will tink the water a very light yellowish color. For the best results, it's good to 'power feed' the male and female to get them fat and in good condition because they will spend a lot of the breeding process eating very little or without eating at all.
You give the male his 3-4 days so he can explore the tank, set up his 'territorial perimeters' and build a nest. Once you see what corner he builds the nest in, add an additional item to the tank. A rock or other 'hide-away' at the other corner of the tank. It will be important later!! Feed sparingly and remove ANY uneaten food! Once he is set up, introduce the female by placing her INSIDE the jar/hex/cube you set in the center of the tank.
Some females can be aggressive or show little interest in mating, which results in fighting and fin damage. By segregating them, the male can pose and strut his stuff until the female is showing signs of submission and interest. She shows this by pointing her head down, clamping her fins, and displaying vertical stripes on her sides. If she doesn't show this display after 5 days, you'll have to replace her with another female or remove both and try again in a few weeks (she may not have built up enough eggs to breed... or may be too old to breed).
If she DOES show breeding display, gently tip her container (which should have the same water level as the other tank) into the water, releasing her in with the male. Do not feed either of them at any time after this event! He may chase her and nip at her fins. She may nip back just a little. This is normal. As long as she isn't fighting back too hard or regaining her body color, it should settle down after a few minutes and they should couple together below his bubble nest. This will involve the male curling his body around the female, a shuddering of both, and then the female or both will sink to the bottom of the tank. She may look paralysed. This is normal. They should also release a batch of cream-colored eggs that the male or both will take in their mouths and spit up into the bubble nest. They may eat a few of the eggs. This is also normal (it's thought they can tell which ones are fertilized and which ones were missed). They will continue this process until the female is empty of eggs. After this, the male should chase her away from the bubblenest.
She will probably duck behind that rock you placed in the tank and once she is out of sight, the male will return to the bubble nest. This is when you should remove the female from the tank and feed her good high protein food to help her recover. After this point, feed the male sparingly and close to the nest. If he's not eating, don't press the issue and stop feeding him. He will take care of the nest until the eggs hatch a few days later. At this point, cover the top of the tank with saran wrap to keep out drafts and DO NOT LET THE WATER RIPPLE! It can and *will* kill the fry!!!! The male can remain in the tank and care for the beta fry until all the fry are free-swimming. After that point, you should remove the male from the tank and begin feeding him good nutritious, high protein food to regain the weight he lost caring for his brood. Also any damaged fins can be treated at this time.
If you'd like help with caring for the fry afterward, I can give advice on this as well.
