how do you open the metering valve to bleed the brakes.
will a pressure bleeder help my situation with the air in the front driver calioer?

my brake warning light wont go out
thanks in advance
steve

Pressure bleeding will require you to hold the valve button closed. There is a special tool, or you might fit a small C-clamp in there... just closed enough to stay on, not actually crush on it.
Manual or gravity bleeding does not require the valve to be held.

The delco/bendix type of warning light valve is supposed to self center. First unplug it from the main switch/valve body to see if the light goes out,
then, if out, check the valve with an ohmeter while unplugged.
If there is continuity between wire pin and valve body, it's offset, causing the light.
If offset, it might have a bunch of crud in it. This is variations of how i've reset some:
Get the brakes bled to where you have a good, or at least some pedal, and have someone hold extreme pressure on the pedal while you rap on the valve body with tiny hammer (4oz or less, tack or plastic hammer). Also rap on it with no pressure applied. vigorously pump while rapping.
Bleed each wheel also with extreme pressure on pedal. If you know which way it is offset to, concentrate bleeding to the opposite end. Rap on valve body. Another variation, open bleeders and then mash pedal, close bleeders. Rap.

If the light remains on after as many variations of this as you can come up with, and the valve still shows continuity at the wire pin, replace the valve/switch.

There is another type of warning light/valve in some combination valves where, if there is a failure, you must open the unaffected (no-failure) circuit and press the pedal down to center the valve (some Kelsey Hayes). If old and cruddy, it might also involve the tiny hammer.

This info should work for the OE 2&3 valve systems, and for combination valve systems.

If you need a new switch/valve, you can get the original style here:
http://www.piratejack.net/proportioning_valves.html
PV5 GM restoration part