You'll need really, really tiny food for the fry. Vinegar eels would be a good starter foods, then as the fry get larger you could move onto baby brine shrimp. You should also be prepared to individually house and feed the hundreds of fry that could possibly result from the spawn, and familiarize yourself with the concept of culling. As for the breeding tank, 10 gallons is a good size. A heater is a must, as is a sponge filter(you'll need an air pump for it). A lid for the tank with a light is also a good idea. The grow out tank for the fry should be at least 20 gallons, again with a heater and filter. Generally, live plants and Indian almond leaves are also beneficial in the breeding/raising of bettas.
I highly suggest reading up on the sticky threads on breeding bettas at the top of this section, they are extremely informational and will give you a good idea of what you're getting into.
I highly suggest reading up on the sticky threads on breeding bettas at the top of this section, they are extremely informational and will give you a good idea of what you're getting into.