Males have a long straight anal (bottom) fin whereas the females have a fan or triangular shaped anal fin.
follow the link below and click on the link for mollies, swords, guppies & platies
you can keep most fish with mollies as long the other fish don't try to eat them. Most smaller barbs and tetras will be fine. Angelfish, gouramis, etc.
Males have a gonopodium, where females have a anal fin, any other livebeaers such as , Endlers, platys, swordtails, guppies would be a good choice to have with them.
Here is what a male looks like, note the gonopodium (circled)
Here is what a female looks like, note the anal fin (circled)
much better, all fixed
that was quick, have you got one of those pens they use on the cricket. The ones they use to draw all over the TV screen. The ball goes here and here and here and there are little lines all over the place