Welcome to AA! You're in good hands with romydooms! As others have said, you will need a heater, and you can definitely have guppies and mollies! But, before you get those fish, you need to
A. Cycle your tank (duh)
B. Figure out if you want to breed
Mollies and guppies are both known as the "rabbits" of the aquarium world, and if you get males and females... Theres no doubt there will be babies. Now, with the stocking you have now, you'll have lots of room for fry (baby fishes), but if you'd rather not go down that road, look into all males, as females can hold sperm for a long time.
my names Lauren by the way, and feel free to Pm me, or any other members if you have any questions!