1990/91 MPV alternator warning

I checked the alternator belt this morning after I woke up, and it looked to be in pretty good condition still. I have yet to try jump-starting the van, but that's next on my list before possibly getting a mechanic to look at it. I'll see if I can get what you're referring to from radio shack.
EDIT:
Forgot to add, but when I turn my key in the ignition, I have power, as in the sound system and lights work, but the engine doesn't even make an attempt at starting. No sounds or anything at all.

So are there any none-mechanic solutions? Maybe something I can simply do at home?

As well, check the width of the belt, and it should be a tad over 1/2 in.
If the belt is narrower than this, the alternator won't give proper voltage at idle.
And, you can tighten it but it still will slip.

The 3 terminals on the mazda alternator are for field, stator, and battery.
When the light goes out on the dash, that indicates a parity of battery alternator voltage.
But, the battery could still be undercharged via. A slipping belt, worn alternator, etc.
The only correct way to determine the battery/alternator relationship is with a voltmeter set at 20 vdc.
The voltage of the battery before starting the engine should be @ 12.80 volts.
!2.8 volts indicates a fully charged battery.
When you start the engine, the voltage should be 14.5 at the battery posts.
This voltage will fluctuate if headlights are turned on, etc.
But, after shutting off the engine, the battery voltage should climb back to @ 12.8 to 13.0 volts.
If you don't fix the front rear-view mirror dome light, this could be a potential electrical short, you know.
Buying a new one is not the answer because the plastic light bulb terminal holder is plain garbage.
It has to be fixed using a new UHMW plastic terminal bridge and the original terminals, with brass screws. 3/32 in.
I have done this myself and don't expect problems for 20.5 yrs.
Also, lubricate the ball bearing at the rear of the starter armature with NLGI 2 grease, and the starter gears.
Lucas Red' N tacky should be ok, but there are better greases from 76 Lubricants, such as Unoba NLGI 2.