Did you just add your hard drive to the PC. You might have to prepare the hard drive before the installer iso recognizes it. I atleast had to do that for my Western Digital hard drive.
As for usb booting...your bios needs to have support for booting via a usb drive. Start up your PC and enter your bios. Find out the area where the boot options are listed...the options must be listed there.
Come back here if you still have problems.