Step 3 of 7
Middle layer edges
Place the four middle-layer edges, each between the two centres of its colours, without breaking the first layer. For each top edge without yellow, turn the whole cube so that the centre of its side colour is in front, and apply the matching basic situation. An edge stuck in another middle place first goes back up: bring that place to the front right, do the "On top, goes right" algorithm, then take the edge from the top.
The basic situations
Hold the cube as the hint says, then apply the formula. In the app, every formula is animated on a virtual cube.
On top, goes right
The edge is on top: turn U until it is at the front, its front colour above the front centre and its top colour that of the right centre.
U R U' R' U' F' U F→ piece in placeOn top, goes to the front
The edge is on top: turn U until it is on the right, its right colour above the right centre and its top colour that of the front centre.
U' F' U F U R U' R'→ piece in placeIn place, flipped
The edge is already at the front right, but its colours are swapped.
U R U' R' U' F' U F→ On top, goes right