How to I get my Rottweiler and new kitten to get along?

I have a Rott that I have had for 7 years and I just got a kitten. The kitten is petrified of the dog, and the dog has lunged at it. I am scared, what do I do? Any helpful tips? How long till they get use to each other? My Rott is a very good natured, loving, dog, and gets along great with strange dogs, so I thought a kitten would be ok. What should I do. I'm stressed! aaaaahhhhh.