There really is no "how". Just put Males and Females in the same tank and you'll have babies. Keep in mind they grow pretty slow and unless you start with a huge amount you'll use them up as feeders much faster than they can breed. If that is what you're breeding them for.
Ohhh since your going to look at them try fancy (and if u want to spend a little more) get one male they have bright long colorful tails and then get 3 females there very less colorful and mostly have blackish tails
Ya that's plenty of space lol just make sure you have some gravel ,rocks/caves(get some from your backyard), & plastic or live plants so the fry don't get eaten by there parents