If you would like to make a rectangle instead of a square then you continue to increase, but only on the side that you are increasing. Notice how the row on the increase side now ends on top of the previous rows increase block. If I was making a square I wouldn’t have added that last block to the row.
Continue increasing on the right side only until the piece is as long as you want it.
When it is high enough then you stop increasing in the exact same manner as you would for a square.
Boxes show the increase C2C blocks. If you were to make it wider instead of higher then you would have more increase blocks across the bottom, not the side. The arrows show the direction of the row. The orange is going left to right and the yellows are moving right to left.
Next up: C2C 103: How to change colors