It sounds daunting but should be manageable. Just follow the instructions.

1. Look for the Create Recovery Media option in the start menu on the factory operating system. If you use a DVD writer it should take 2-4 DVD-R discs.
2. Shut down computer and stick DBAN disc in the optical drive. Start computer. DBAN should start instead of Windows.
3. Once DBAN is done, shutdown computer and replace DBAN disc with Start Recovery disc. Start computer and follow on screen prompt to reload factory OS.