The only thing left to do is return the power to the computer. Plug the AC cord back into the power supply and flip the switch on the back into the On position.
Once these steps are taken, the hard drive should be physically installed into the computer for proper operation. Since floppy drives are very standardized, there should be no formatting or BIOS settings necessary to enable it. The only problem that could happen is a reversed floppy cable. This is easy to spot by the floppy drive light being on continuously while the computer is operating. If this is the case, double check to make sure the floppy drive cables and installed in the proper direction.