It's difficult to give 'detailed instructions' or any instructions when your post is so vague. What exactly is the problem? How is the sound not playing back correctly? If you take the time to be more specific then you're more likely to get relevant help.
Video Producer/Creative Director
Creative Dynamic Video Production
To do the job PROPERLY in AE, you need to get a third-part frame rate conversion plugin. ReelVision and Magic bullet both make one. Neither is especially easy to use -- you have to select from a vaiety of motion estimation algorithms -- and they might not work very well in shots with extreme motion.
If you're willing to settle for "it's not perfect but it might do", look up the tutorial on videocopilot.com.
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA