1a. Make a Cross on the Top Layer
If you have already solved the first layer, you can skip to Step 2.
Otherwise, hold your Rubik's Cube with the yellow center piece facing up. Find the yellow & green piece and move it to the green side, the side that is green in the center.
Twist the green side 1 or 2 quarter-turns to move the yellow & green piece to the top. Your Rubik's Cube should look like this:
If the two colors don't match up, flip the yellow & green piece like this:
Solve the other 3 sides the same way so you have a yellow cross on top. You won't mess it up if you use the bottom layer to move pieces around. Watch the video at the top if you get stuck.
When you have a cross on top, you're ready to solve the corners.