I'm also completely stumped how to play the game. I somehow got past the first level by moving the mouse wheel while randomly trying all kinds of buttons to see if they do anything. Then I got stuck on the second level (the one with the weights) where I get that the idea is to move the weights onto the scale, but I have no idea how to *do* that. Drag and drop doesn't seem to work, neither does clicking the weight (which makes it move by one or two pixels) and then clicking the place where I want to move it.
You should at least amend your project page to include the controls, otherwise I think you're not going to get much worthwhile feedback on the rest of the game.