I find myself getting confused with the meter in the viewfinder when I manipulate the exposure control on my camera. I have not processed anything yet, so I do not know the effects. Could somebody help me?

If I'm shooting 64T, and the meter shows the F-stop at 2.4, and I move the autoexposure so that the meter increases to between 4 and 8, am I letting less light in, or more? If I move the meter the other direction, then I get the underexposure warning.

Please help.