I am having trouble locating the starter for my civic. Is it behind the engine, underneath? Am I able to get at it with a simple floor jack? Also, can I test my starter while it is still installed?

The starter is located just behind and below the distributor (on top of the transmission). You can't miss it. The link below will help you test it, while installed:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-honda-civics-46563-3.html#post235560

Here's how to replace your starter:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-honda-civics-46563.html#post219985

No need for a jack--easy access.

If you can't figure out where the starter is on a Honda, you shouldn't be working on it at all.