In this step your goal is to get all white edges around the white center as shown in the image, you may have noticed that the edges are placed according to the centers in the middle layer like edge with orange and white is placed between centers of orange and white, same for green and all other colors.Almost all of this step is to be done by you but here is some help:-
If you are struck here try this:-
F U R Ui (If you have problems with move notations go to Introduction page)
-:Proceed to next Step