When you get the key (the "Who Am I?" puzzle), use it to open the upper of the two chests. Take all the stuff out of the chest. Move the chest, and open the chest below it.
There will be a toy rocket inside.
Take it, and go outside the yurt. Put the rocket on the ground so that it is standing (it can be a bit tricky). Then use it with the left mouse button.
Watch the results, and the achievement will unlock.