Back to topic please?
What size tank do you have? If your trying to breed mollies I would go with a 20-30g+ along with a smaller grow-out tank. You WILL have lots of fry to deal with, along with the fact that mollies get pretty big. You don't need more than a 1:2 male to female ratio for sucuess.
I reccomend putting the female in her own tank when she starts showing signs of pregnancy (VERY noticeable belly, gravid spot) Use either s sponge filter or put a pair of pantyhose over the intake tube of your HOB filter. Get a little bit of java moss (will become a lot quickly) and go with a bare bottom tank (not neccesary, but helpful)
Feed the fry live food, and be prepared to do water changes.