I'm assuming you mean how to power up the plug to start the engine...

The plug heats on about 1-1/2 volts... for O.S. engines, it will glow orange at the proper temperature. The plug can be connected to a power panel (which is a thing that manages power for all your field needs) or to a 1-1/2 volt dry cell with a lead and a glow plug clip, or it can be powered with a self-contained battery unit that includes a connector and perches right on top of the plug.

If the engine doesn't seem to fire, you can check the plug by watching the current draw on a power panel (there should probably be an Amp and a half or so going through it if I remember right) or by removing the plug and looking for the orange glow when it's connected to power. If the element glows red, then it is too cool, and if it's very bright or almost yellow, then it's too hot... if it doesn't glow then you've got a bad connection, a bad power source, and/or a bad plug.

There's not that much more you'd need to know about the glow plug initially, but there is a good bit more to know about starting and running an engine. Is that what you needed to know? Is anybody able to help you get the engine running? It can be frustrating until you get to know the individual engine upclose and personal.