I think this bike comes with a flip-flop hub. What that means is that one side is a freewheel and the other is a fixed gear.

But just for your own knowledge, a real fixed hub has stepped threading so that you can 1. screw the cog on (clockwise). 2. screw the lockring on (counter clockwise).


For the freewheel, you will need a proper freewheel tool to get it off.
For the fixed cog, you will need a lockring tool to get the lockring tight. You might as well pick up a chain whip as well incase you want to take it off.