Introduce Yourself <post there please, then read the info they give you. Questions about guides should be asked in the guide.
the prepare sd card part is referring to on screen instructions, not formatting @ that point. Put the files back on the card and pick up where you left off. Only format your card when the guide specifically say "format sd card". Follow the directions exactly as they are written and you will be fine. btw...skip the darkcorp option.