Start by tying a loose Granny Knot in one end of your two working strands...

Now take one end of your central strand (your shortest piece of scoubidou) and stick it under one of the outer loops of the Granny Knot...

Like this...

Pull your central strand through the Granny Loop until you've come to the center of the short strand, then pull the Granny Knot tight.

Lay your strands to match the picture, where your central strands are on top, with one color on the left, and the other color on the right.

To start the stitch, choose a color you will ALWAYS start with (green in this example) and make a loop of this color OVER the central strands as shown.

Now take the other strand (the black in this example) and place it OVER the looped strand (green here).

Continuing with this strand (the black), take it BEHIND the central strand (red)...

...and UP THROUGH the loop made with the first strand (the green loop).

While pulling the strand tight, it should look like this.

Pull this first stitch quite tight, making sure to also pull your central strand (the red) DOWN out of the stitch, as it will want to jump UP out of the stitch. You want to see as LITTLE of the central strand (red) as possible before continuing. You're now ready to continue...