Mac os x install DMG?? Need some help

INB4 this gets utterly derailed into a torrenting debate thread.

If you have a USB drive that's big enough, you can use Disk Utility to "burn" the .dmg to the drive, making it a bootable drive.

When rebooting, press and hold alt/option and select your bootable drive.

 

You'll need to buy a DVD large enough to burn the DMG file onto the DVD or buy a USB flash drive that is at least 8 GB and you can then boot from the USB in order to install it. If you don't have either I can't help you so going into detail would be pointless. If you acquire either one and come back here, I'd be happy to help you out.

He would also need to format the drive with an Apple Partition Map if he's booting a PPC machine. And you don't "burn" anything to a USB flash drive, you transfer the contents of the DMG image to the USB drive via the Restore function, which then makes it bootable.