How do betta fish make babies?

smaller/bigger in size, less/more aggresion, not flaring at other bettas or reflection/will flare, shorter/longer finnage (with aception to plakats), less colour/more colourful... you can see a...

I hope this isn't seroius, but he's a boy so no. Unless the "boy" is just actually a longer finned female

You feed it and care for it also when its 29 days old feed it brine shrimp.

You would surely be aware if Bettas have been spawing in your tank. If they have, and nothing else has been spawning in there, then in all probablility the tiny fish you can see will be Betta.

they lay eggs