Testing an oscilloscope
I guess you have a problem with triggering.
Follow following 3 steps:


Select correct trigger source. You probably have a choice between CH1, CH2, LINE, EXT. Select CH1 if the signal is picked up at channel1.
Select correct trigger mode. You probably have a choice between AUTO, NORM, and a few other modes. If you select NORM the beam will only be visible if trigger is triggered (see 3.). If you use AUTO, you should always see the beam. So select AUTO.
If you now see the signal but it is not standing still trigger is not tiggering; probably because the trigger level is beyond the signal range (i.e. too low or too high). So select an appropriate trigger level