Q&A

The battery light came on because it was discharging (losing power) while you were driving. Normally the alternator charges the battery while driving. The Alt. is driven by the Accessory belt on the left side of hte engine. Very likely your belt is loose and even though the engine is running the belt is not spinning the alternator pullet fast enough to charge the battery. The most likely cause of loss of tentsion is a broken tensioner, a spring loaded pulley on the left side of the engine. This is a fifteen dollar part.

But to get to that part you have to do a lot.
Remove the left front wheel. This is to get to the belt on the side of the engine, which is horizontally mounted (Perpendicular to the cars direction of travel, or sideways)
Remove the inner fender/shield. It is clipped in place with push through buttons best pried loose with a screwdriver and grabbed with a pliers. The lower edge is held on with flat push on clips. (This will make MUCH more sense when you actually look at it.) Amrk the flexible shield as UPand Front cause it's wierd shaped and hard to remount. Look at the side of the engine. There are things like an alternator, an A/C Pump, a power steering pump, and a crankshaft. In the center is a black pulley not connected to a big thing. This is the tensioner. Ease the accessory belt off the nearby pulleys (replace it ) and detach the tensioner body from the engine. It is held on with two bolts (10MM heads) that go directly into the engine - (the upper one required a 1/4drive 10mm socket and dexterity) replace with the new part, be firm but don't overtighten the bolts in an aluminum block (Do not Strip the threads). To replace the belt look at the "Belt routing diagram" on the top of the engine, over this under that up here back down there.. Be sure to notice which pulleys have ridges, and put the ridges on the belt in all of the slots. BUT to get it to fit you have to put a wrench on the bolt in the center of the tensioner and push it back on it's spring, until you can slip the belt over the nearest pulley - which is the crankshaft itself. (Big thing with ridges on it right at the bottom of everything visible). There is a picture next to the belt routing diagram of how to slack off the tensioner pulley, which only really moves in one way- against the spring. This takes very little pressure. If it feels hard to do you are probably pushing on it the wrong way.
Check the tension (poke the belt, it should be under tension, I.e. tight). Ask someone else to look at the belt routing diagram and the belt you installed. If they agree it's fine...
Start the car. Watch the belt. OK.
Put the wheel well curtain shield back in place. Pop the inner fender into place. Remount the wheel.
Drive off into sunset.
I don't know why the site thinks I am ProChevy. I am not.