first thing you need is to rip the movie to get the encryption off. U can use smartripper or dvd decrypter. Both are good progies to rip.
After that you have all your files from your original dvd9 disk(7-9gb) Now u need to compress all that data to fit your dvd+-R 4.7gb disk (dvd5).
I recomend you use dvd2one as this is the most used and the offical support forum for the product is right here. Rene will help you out with anything u need on that.
Need me to clear anything else up? Hit me on the PM or ask away.