Unless you've researched this, don't try to breed your bettas. Breeding and raising bettas takes a lot of time and effort. Don't try it just because it will be "fun", or becuase you want to see what the babies will look like. Unless you know exactly what you're doing, there's a good chance you could lose one of your bettas, and a great deal, or all of, the resulting offspring (if you're lucky enough to get any).
Breeding bettas is not as easy as buying two fish at Petco and dropping them in a tank together. It takes conditioning, good timing, and a lot of patience. Temperature has very little too do with it. Your bettas will have to be the right age - somethings that's hard to tell if you bought them from an lfs.
First of all, are you ready to properly raise 50-150 babies? You'll need live cultures to feed them, a large enough tank to raise all the females, and containers for each male. What will you do with the offspring? You can't just drop them off at your local pet store.
If you really want to do it, then do lots of research. Even with a lot of knowledge, your first time may not be successful. Takes a lot of know-how, a little practice, and a lot of luck.