In the fourth step we want to form a yellow cross on the top of the cube. Don't worry if the side colors don't match the side centers because we will send the pieces to their final positions in the next step.
At this point you can have one of these patterns on the top of your cube. Use the algorithm below to jump to the next state until you reach the cross.
Dot – we have to apply the formula three times when all top edges are oriented wrong and there are no yellow stickers around the yellow center. Make sure you reorient the cube in your hands after the first stage because the "L"-shape will be upside down.
"L"-shape – You're two algorithms away from the target. Make sure the yellow edges are located on the left and back positions as illustrated.
(There's a shortcut which jumps from the "L"-shape to the cross in one step, reducing the solution time: F U R U' R' F').
Line – Perform the algorithm once, holding the line horizontally and you're done.
Cross – The cross is complete, you can go to the next level!
We have the cross on the top but the sides of the yellow edges don't match the side colors yet. We need to put them in their final destinations.
To sort this out we use an algorithm which swaps the Front-Up and the Left-Up adjacent edges marked with the arrow.
In some cases two opposite pieces have to be swapped which needs to be done in two steps.
Perform the algorithm once, then rotate the cube to make sure you are changing the right pieces in the second round:
R U R' U R U2 R' U y2 U y' R U R' U R U2 R' U
At the end of this step you should have an almost finished cube, where only the yellow corners are left to solve.