When you say 'graph', do you mean like a stored image on the scope of a waveform? Like in digital storage scopes? Or do you mean just voltage display? I assume you are looking at some AC waveform, do you know the frequency? There is usually a BNC or two where you input the voltage, usually under ten volts AC, high voltages can damage the scope. Then you have to trigger the signal, either internally or externally and you have to have the right time base dialed in. If you are trying to display a frequency of 100 Mhz, you would need to have the time resolution at somewhere around 1 to 10 nanoseconds per sweep. If you tried to look at 100 mhz and had 1 millisecond dialed in you would just see a band of light with no signal resolved. Hope that helps.
Don, AI3N, Delaware Lehigh Amateur Radio Club, Allentown/Bethleham Pa.