Hey John, welcome. You don't check voltage at the plugs, you check for a strong blue spark at their gaps when cranking the car. The plug voltages are way higher than the battery but they only occur for milliseconds. You need five things for car to run: fuel, air, spark at the correct time, good compression, and correct valve timing. Check the easy stuff first.
1. Is there gas in the car?
You should be able to check this on your own.
2. Is fuel filter clogged or good?
Pull it off and try to blow through the inlet. If you can't or it's very hard to blow through, replace it.
3. Is the fuel pump delivering fuel to the injectors and at the right pressure?
On the firewall there's a fuel pump test connector on the passenger side. It's two prong and yellow in color, right next to a large green connector. If you jumper the yellow connector terminals and turn the key on (but not to start), the fuel pump should run constantly (it's under the back seat on driver side) and you should be able to hear it run. You can attach a fuel high pressure gauge to the fuel filter hose and check the pressure that way.
WARNING: Do NOT run the pump with the fuel line open!!! You will get a geyser of gas spraying everywhere if the pump works good!!! Pull the jumper off the connector when done.
NOTE: The fuel pump does not run normally until the key is turned to start and the air flow meter starts to move from the air moving into the engine, hence the test connector for key on engine off testing...
4. Are the injectors working?
When you crank the engine, listen for them clicking. A stethoscope or long screwdriver pressed against each injector will help you hear this.
5. Is the air filter clean?
Duh.
6. Is there spark at the plugs?
Pull them out, lay them on the valve cover, and crank the engine. You should see a strong blue spark at each gap. The metal shell of the plug must be grounded against the valve cover for this to work. No spark means distributor isn't working right or no power to it, or the coil may be bad (check connector at coil too for looseness).
7. Is ignition timing correct?
You'll need to check this with a timing light.
8. Are all the cylinders showing good compression and within 10% of each other?
When plugs are out check compression.
9. Is timing belt in good condition and all valve timing marks aligned?
You can pull the top part of the timing cover off to check the cam gear marks and crankshaft pulley for alignment.
techcapri.com has all the shop manual info. If you can't get to the site I can send you the applicable PDF files.
This is just a basic rundown of stuff to check. You may just have a loose connection or your ECU may be fried from reversing the battery cables. You just have to start troubleshooting things methodically and eliminate the stuff that works.