Didn't realize you were using Nero Express, but yeah,that's usually the freebie that comes with burner.
Ok,,once you open Nero Express,dropdown the list of 'which recorder' to use. Choose the recorder that has (DVD) at end of listing. On the next window that opens,there should be a dropdown menu at bottom right showing the size of the DVD disk. It should show 'DVD5: 4483MB'. Use this unless using a dual layer disk. Then just open the files you want to burn and drag n' drop them to the left window 'til it reaches max size or you have all you need...