What type of files do you have now? Nero Recode is what you want to use to burn the dvd ... burning rom can do it too but recode is a bit simpler to figure out.
If your DVD on your hard drive has a folder named "Video_ts" than that's what you need. Open recode, chose "Recode an Entire DVD to DVD" or one of the other options (Recode Main Movie to DVD ... Remake a DVD) if you only want to copy SOME of the original DVD. Click on "Import DVD" or "Import Titles" and select the "video_ts" folder. The rest should be pretty easy.
If you have an ISO file, recode can't view the contents of it. (an ISO is a disk image, kind of like a zip archive of all the files on the DVD). Inside the .iso is the video_ts folder. You can get it out with a freeware program called ISO buster. Maybe Nero Burning Rom can get it out, but I haven't ever tried that.
There's a program (free) called DVD Decrypter ... you can use that to rip and burn dvd's (but you'll need your nero (or some other program, the free DVD Shrink seems to be popular) to compress the contents of a DVD if it is bigger than the blank you want to put it on).
I'd use DVD Decrypter to burn the dvd if it is an .iso file smaller than 4700000kb. And it's best to use it to copy the dvd to your hard drive first, too. Use file mode if you are going to have to compress the contents with recode.
There's plenty of guides online.