Zinc, copper, a blotter paper, a grain of white, and copper sulfate solution make a battery by creating a full circuit through from the zinc to the copper sulfate to the copper to the light bulb and then to the zinc again. The blotter paper prevents the battery from short-circuiting.
The zinc releases a negative and the copper gets a negative. This makes zinc the positive side of a battery and the copper a negative side. This is how zinc, copper... make a battery. Yay.