Welcome to the forum, anniep34.
Just to check a few things :
You did use Nero to try and burn those DVDs, not just drag and drop files into the writer in Windows explorer, right? I'm asking because windows explorer can burn CDs this way, but not DVDs.
When you first start Nero express, there is a drop down box which lets you choose what drive to use to burn stuff. It should say something like "HL-DT-ST DVDRAM GSA-H10A" (which means write to your new burner) rather than "Image writer xxxxxx" (which means write everything as image file to your HD). If this is not what it says now, just click on the drop down box and change it.