One of the scales will be DC volts. this is the scale you read for DC voltage reading.

  Put setting on DCV, one notch above 12 volts. For instance if the next level is 50v, so be it. One of the test leads goes to DCV, the other to common ground. Start vehicle, Connect test lead (common ground) to neg. of battery, the other to the pos. Get the reading from the 12volt scale. Max output of the alt. is around 14 volts. battery voltage is 12 volts. Take second test with lights on to give it a load. If voltage is say 12.6, it's not a good thing. 13.2 is about right with a fully charged battery, thats mostly what I saw on most cars. But this can vary between cars. 

  That's pretty much as simple as I can put it without going into detail.

  I had one of them old Multimeter in my hands a few months ago, and it sure is bulky and heavier then anything we use now. But it was state of the art.

  On our multimeter's we had to zero them every now and then.