Top left · yellow front
Step 1 / 4
U': Two layers around the top corner: turns counterclockwise (looking at the top corner)
The yellow-green edge is at the top left, with yellow facing you.
U' moves the edge to the right with green in front. Then do L' U L.
Step 1 of 4: U'. Two layers around the top corner: turns counterclockwise (looking at the top corner)