The time to research the fishes needs is BEFORE you bring them home from the fish store.
The mollies need hard alkaline water with pH between 7.5 and 8.0 with 12 to 15 dgh, Ammonaia and Nitrites must read zero all day, every day and temp around 80 degrees F.
They are largely herbivores ,who will appreciate veggie flakes crushed to near powder for the babies along with occasional meaty foods, such as brine shrimp,blood worms,or tubifex made small enough for the fry to consume. Babies also would benefit from three to four SMALL feedings each day.
Floating plants either real or artificial ,will give the fry a sense of security.
At approx four weeks old fry should be large enough to be placed with adults without fear of predation.
Monitor the water closely. Three to four feedings a day, along with the numbers of fry ,often can result in the need for larger more frequent water changes.