Place a dual layer DVD to the DVD drive of your computer and open the Nero Burning ROM which is one of burning applications contained in the Nero 7 burning suite. Start a New Project and go to Data > Data DVD, drag and drop the files you want to burn to the main window and click the drop-down menu next to the capacity meter. You will be able to select DVD5 and DVD9. Select DVD9 to switch it to dual-layer which can support up to 8.5 GB of data. After you add the files, press the Next button, enter a name for your disc, select a burn speed no greater, then 4x and click Burn.