You have started correctly by decrypting to your hard drive. Make sure to remeber the path to the folder you put it in.
Next open Nero Recode. Open "Remake a DVD". Click on "Import Titles", and point to the folder holding the decrypted files. Essentially, it will then do its own thing and give you a list of the contents, their size, their compression ratio and a great deal of other information.
The rest should be intuitive, where you can select what you want to include on your DVD, or just click "next", and you will have your movie.
Nero Recode is a most excellent program, and after a few trials and doubtless a few errors, burning movie DVDs will become a doddle.