How do I create a bootable drive

Do you have a new system? If you do and your system is still able to power up you might be able to get the system into Target Disk Mode Use target disk mode to share files between two Mac computers

If not don't fear you still could take the drive out and then using either a 3.5" hard drive case or a Universal Drive Adapter will allow you access from the second system. Here's how to take it out: iMac Intel 27" EMC 2390 Hard Drive Replacement

But before you go down this path have you tried running diagnostics to see whats wrong with the system? Locate the grey CD/DVD disks that came with your system use it to boot up your system.