Can you tell us how your video files are formatted now, on your hard drive? That is, what are their file-extensions?
Are they the file-sets copied from existing DVDs? (So, there's a folder with files named "VIDEO_TS.IFO", and some .BUP files, and some sequentially numbered IFO files?
Or do you have files named with .MPG or .TS or .MP4 extensions? (.AVI, and so many others, too.)
NERO has a Start Menu that offers a choice between burning CDs, or DVDs, or BluRays. That's the first choice you'll need to make - in this example, you'll want "DVD" to be selected.
This will display a subset of application icons, and one is called DVD-VIDEO.
I'd select that, and then Nero gives me a 'two-pane' left to right screen where my Hard Drive's contents are displayed on the right-side of my screen, and my Left Side is blank. That's the 'work space'. I drag my DVD-Files from right to left.
And then select BURN.
That's the simple steps, but we could probably use your answers about file-formats first.