Hi April! Welcome to dancing! There are lots of ways to start dancing.
The quickest way to learn is to take private lessons. You can find a teacher at a ballroom studio in your area. Are you in the U.S.? If so, try this site or accessdance.com. Or try the yellow pages. I always recommend you take sample lessons at a couple of studios before you decide where you want to take lessons (and don't let a studio pressure you to buy a large package of lessons unless you're sure that's what you want).
If that's not feasible, there are lots of other alternatives: group classes at studios, classes at YMCAs, community centers, etc., college dance groups (some are open to non-students). Uless you live in a remote area, you're bound to find some way to learn to dance.
One small caution: if you've watched top level dancers on TV, do be aware that it will take quite a while for you to be able to move anything like that. But the journey is very rewarding in itself.