How do I bias the tubes in my amp?

Just bought a Golden Tube Audio SE-40 and sat down to bias the tubes so I could listed to my first tube setup and found that my Voltmeter only goes up to 400mV. The tubes need to be set at 640 - 650mV. I went to Radio Shack to buy a new meter and all of the meters they had cut off at 400mV. I'm sure there is a simple answer to this but I don't have it. Can anyone help me by telling me how to do this, or where to get a better meter?
check it again. I'll bet you find you are checking milliAMPS, not milliVOLTS. The current, not voltage, is what you're adjusting.
Yes I thought of the mA thing. This meter will read in Volts, Millavolts, Amps and Millamps. The meter is digital and cuts off when the reading gets higher than 400mV's. I can read Volts up to 1000.
You need to use the volt setting. Set your bias for .650 volts, which is the same as 650 millivolts.
Milli means one thousandth. If your meter is auto ranging, set it for volts and it will select the proper volt range for you. If it is not auto ranging, you will need to select the lowest volt range.
Thanks Bruce! I appreciate the help, I thought I'd never get to hear this amp.