I accidentally hooked up the battery cables backwards on my 1990 civic, now I have no power whatsoever. Am assuming it is a fuse, which one is a likely culprit and how do I know if its bad? The battery is new and has a charge, yet nothing is getting any power

I assume you checked the fuses on the box on the right front wheehousing and not just under the dash?

Test all under hood and under dash fuses with a test light or multimeter:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post252145

Be VERY thorough!

These situations can be costly, if the ECM, alternator, or various sensors were taken out.