The electricity to light your light bulb comes from the battery - the wire is what the electricity moves through. An important thing to consider is how the battery works, there is a chemical reaction inside that puts extra electrons at the + terminal. When a wire goes from the + side to the - side, the electrons flow through it to go the - side. If your light bulb is in the middle of the wire, the electrons will flow through the light bulb as well, causing it to light up. So to do this in your case, you actually need two wires. One wire will go from the + side of the battery to one side of the light bulb, the other will go from the other side of the light bulb to the - terminal.
