How to turn on the beep sound for the nikon D5000 when it is in manual focus?

I have a nikon and i love it but it's very hard to use the manual focus because the camera does not beep at me when it is in focus. I have heard and seen other cameras that have this feature just i don't know how to turn it on for my camera. If there's any other way to know if the image is in focus please let me know.

Whenever I have a question like that, I always refer back to the cameras manual. If you look on page 158 section D1: Beep, it is discussed. OR page 31 #2

http://www.nikonusa.com/...000_en.pdf

You do not need the camera to beep to help you focus. If you're using the viewfinder, you will see an "focus indicator" that lights up indicating that the subject is in focus. When you see the indicator go on, it means its in focus and you can take a picture.