How to dance BEST ANSWERS GETS 10 POINTS?

I want to dance like Rihanna, because she number one is my inspiration, and I like the way she danced before she changed. It went back to her roots, and it was all about having fun. So anyways I want to learn how to dance. The problem is I'm only 15, I'm home schooled, I don't have any friends to show me, and I rarely get out the house, not by CHOICE! So anyways yeah I can't go to dance lessons, and I don't have rhythm, well I have some but I'm stiff too. So are there any videos that will actually help?