Subsequent pictures are nostly simplified views of the upper layer from above. Hopefully they are clear enough.
Arrows point to where individual cubies transfer to.
For clarity, the transfers of corner and edge cubies are shown in different colors. For now we don't pay attention to the corners. Now we transfer the corners into their correct positions without regard to their orientations. Needless to say, we use algorithms, that do not change the orientation of the edge cubies, obtained in the previous step. Next we use algorithms, that orient the upper corners, but do not transfer them, and also do not change orientrations of the edges.