Sorry, I assumed you were going to use it as an ohmeter too. But there should not be any power on there. Your meter should go from zero to infinite when the points break.
Mark
To expand on this,
No matter what method you use, set the points gap as per the procedure in the manual first. If that's not right, your timing never will be either.
Positive meter lead = blue wire or yellow wire
Negative meter lead = ground
When using an ohmmeter, do the test with the ignition OFF. When the points are closed, there will be little to no resistance. When they open there will be infinite resistance.
When using a voltmeter, do the test with the ignition ON. When the points are closed, there will be no voltage indicated*. When they open, you should see approximately 12v (battery voltage).
When you use a test light, do the test with the ignition ON. When the points are closed, the bulb will be off. When they open, the bulb will be lit.
mystic_1
* Your voltmeter shows the "difference in electrical potential" between the test points. When the ignition is on, current is wanting to flow from the battery, through the coils, and down to the points. When the points are open, current cannot flow so there's a difference in voltage potential between the test points. When the points close, the circuit completes and your test points are essentially connected to each other. There's still 12v flowing through the circuit, but since the electrical potential is the same at both test points (+12v) the meter reads zero. This same principle explains the behavior of the bulb in the test light configuration.