We can't change the amount of electricity that comes from a battery. Each ordinary pencil-shaped battery gives out 1.5V (one and a half volts) of electrical pressure. You will find this printed on the side of the battery.
Bulbs also have their working voltage printed on them. Usually it is 3V (three volts). So you need 2 batteries (1.5 + 1.5 = 3) placed in line to match one bulb.
