Wd 500 gb hardrive not working, but lit up.

Okay, so my friend gave me this hardrive, because she just bought a 1tb hardrive, i dont know much about this hardrive, ive plugged it in. the light comes on. but my pc wont read it, its a windows 7 home premium.
ive tried a few cords. one thats super short and one thats really long, (if that matters), im not sure what to do. i wasnt sure if i needed drivers on my computer for it to be found or what.. im not sure if its bricked, it was on a mac once before if that matters, which im sure it does. if i could get some help that would be nice. im confused as hell.