1) You need a floppy drive
2) You need a motherboard compatible for a Floppy Drive (Needs the FDD connector, which is different than IDE).
3) The required cables.
4) A case with an open 5.25 external slot
At this point, you connect everything up to the motherboard and Floppy Drive and boot into your BIOS to verify your BIOS are recognizing it. If it is good to go there than just boot, as normal and be good to go.