Step 8: Positioning the 4 remaining middle pieces
You should have one side that has the right middle piece, but it doesn't have to be in the right orientation.
-If you do, then look at the cube from that side (the one with the correct middle piece between the two corners) and preform one of the two algorithms (don't look at the first picture, that's just for fun, look at the second picture)
You'll either need to shift the middle pieces one way or the other. Based on which way you need to go, right or left, do the appropriate algorithm on the 2nd picture.
-If you have more than one or none in the proper orientation, use the "scramble" algorithm on the 3rd picture, looking at any side when you do (so long as you don't rotate the cube up or down), then start this step over again