The hard drive became unusable on this new homebuilt computer
The motherboard comes with a driver/utility disk. Also, the motherboard/system drivers are available for download at the motherboard's online product page. You are not following method 2 correctly. Go into BIOS and set the first boot device to DVD. Insert the Vista installation DVD into the DVD tray and 'save and exit' BIOS. When prompted to 'press any key to boot to the Vista installation DVD' press any key at that time. I would suggest asking for help from someone who knows more than you do when installing Vista. Ask a friend to help or take the system to a shop where they know how to install an OS.