If you have Nero Express (Start-Smart) Open it and in the top right-hand corner select DVD and then Select: Copy & Backup and then: Burn Image to Disc.
If you don't have Express, just find an option that says Burn Image To Disc and then you will be able to browse for the image. The image that you're supposed to burn to the disc is the one that has the .mdf extension and is obviosly bigger.
If you have Alcohol 120%, you can burn the image to the disc by running alcohol and selecting Image Burning Wizard and then browsing for the file that you want to burn to disc. Don't worry about the other smaller file.