Move the wires around by dragging them. The green battery has power, and the blue contact points are corners. Hit space to rotate wires. if u dont put the wires on in order (battery to 1, 1 to 2, 2 to light) it wont work.
If it isn't lighting up, try hitting the flag. It normally works though. Sometimes when you move the wires, it acts like you hit the stop button. If anyone has a fix for that bug, put it in the comments below.