You unlock SECRET 1 after completing a few levels in PRIMARY 2. You'll also need to complete some levels out of the first 10 in SECRET 1 before the full twenty levels are available to you.
Keep mashing
as quickly as possible, and then create a drawing inside the scale, and move away as fast as possible, or you will drop the object. Make sure to keep holding the draw button so that the scales can't tip, then just wait until the 3 second timer counts down.