This step will complete the entire cube!
While those 21 moves may seem intimidating, you really only need to learn 7 new ones. We will be doing the same move twice (notice in the Steps that steps 2 and the are just reversed), and then we will be left with a cube that will just need to sides re-rotated with Step 6 to finish off the entire cube.
This technique will rotate two adjacent side pieces together.
The hardest part of this will be keeping track of each sub-step as you go throughout the move.
With both pieces on the top layer: one of the target pieces facing you, and the other to the right