yep the top red line, basically your cutting the new growth and new leaf growth off, what it leaves you is the stem and the 2 growths at the node, these 2 then grow and become the top of the plant, so then you have got 2 main tops instead of the 1, your removing 1 main top and new leaf growth to give you 2 main tops, its pretty easy and the plant recovers well from topping,