Make a loop with your first piece of rope. (I had no rope or cord for this, sorry!) Make sure your tail is under the main length.
With your second piece, lay it under the loop of the first piece of rope.
Bring the tail of the second piece OVER the main length of the first piece.
Then the tail of the second piece will go UNDER the tail of the first.
Bring the tail of the second piece all the way around (to make it's own loop) but thread the tail OVER blue, then UNDER purple, then OVER blue of the first rope loop.
Pull it tight. It looks terrible with ribbon, for obvious reason, but if you knot with rope or cord it will look really good.