Please note that all data on the Mac's hard drive will be erased, so backup all important files before proceeding. To do this, look towards the top of the screen and click on Utilities from the top menu and then click Disk Utility from the drop-down menu. To install OS X Snow Leopard from the USB drive, you'll need to reformat the Mac's hard drive. Now that you've created a Snow Leopard USB drive, let's use it to install OS X Snow Leopard as well as access Terminal, Disk Utility, and other OS X utilities.
In the center of the window you'll see two boxes: one labeled Source and another Destination.
