emmag21
Odds are (unless you are extremely unlucky) that you'll have at least one female. The males will find her. Along with what drewry and oldman47 said you also have to make sure they comfortable in their environment and that they have places to lay the eggs. This sometimes depends on the species. Mine for example like amazon swords, java moss, cobomba and sometimes the glass sides and ignore the other plants. I can't prove it but I think that a low pressure weather system moving in can also help. They won't breed if they are being harassed by other fish. There are a number of sites that give specifics for you species (which you haven't mentioned.
Some members of this list have gone years without having theirs breed.
Good luck.