A volt meter is an invaluable tool for working with electricity. It can quickly tell you if your circuits are complete and if the correct voltage level is being passed through the circuit to perform the function you are trying to achieve. There are many different styles of volt meters, some analog and others digital, but the basic method of using a volt meter is always the same.
Separate the two leads that came with your volt meter. Usually, one will be red and one will be black. The black lead is the negative (-) lead and the red one is the positive (+) lead. Each one has a probe (a needle-like end) and a plug.
Plug the leads into the volt meter. Usually, only the negative connection is identified on the volt meter's case. Look for the "-" symbol. The positive lead should be plugged into the other connection.
Turn on your volt meter. You should see the needle on the dial jump a bit; some units also have LED lights that indicate the power is on.
Set your unit to the type of current you will be testing. On a dial volt meter, turn the dial until it points to the correct type of voltage (for instance, the mark on the dial that indicates DC; a voltage range may also be indicated). For digital types, select the type and range of volts.
Take the positive lead (red) and pierce the plastic covering of the wire you are testing with the "needle" end of the lead.
With the negative lead (black) pierce the casing of the wire about 12 inches away from the positive lead. You want the negative lead to be farther away from the power connection than the positive lead. For instance, if you are volt testing a wire that is running from a fuse box to an electrical outlet, the positive lead (red) should pierce the wire closer to the fuse box and the negative wire should be closer to the electrical outlet.
When both leads are connected, read your volt meter and note the amount of voltage passing between the two points of the lead.