You will either have one side of the cube solved or no sides and just the top and bottom solved. If you have one side solved then hold your cube so that that side is in your left hand and do the move below until the cube is solved.
If none of the sides are complete then do the move below one time and then one side will be solved.Now hold that side in your left hand and do the move until it is all solved.
Ok with this move you have to turn the back side of the cube(the part facing away from you)
I am going to show that with the word back on top of that turn.Just reach around to the back and turn in the direction of the arrow just like it was the front only do it on the back.