Finding a GRE testing center is pretty simple. The Educational Testing Service (ETS) has an easy-to-use testing center locator on their website, located here. All you have to do is select a few options for your location, and voila!
When I took my GRE, I was living in Houston, and the nearest one to me was in an area of the city that I wasn’t familiar with at all. A few days before I was scheduled to take my GRE, I made a dry run out to the testing center so that I would know exactly how to get there on the day of the test. The last thing you want is to get lost! The stress of trying to find the building and getting there on time might mess up your ability to concentrate during the test, so I strongly suggest that you find out where it is and make sure you know how to get there. You might even want to look up an alternate route in case some unexpected construction suddenly pops up.
My testing center was a pretty standard-looking commercial building. The actual testing area was just a large room with a few rows of computers, not unlike a standard computer lab you can find at most schools. There were other people around me taking tests at the same time I was. I don’t think they were all GREs either. I’m not sure, but I think some were taking the TOEFL, and some might even have been taking their CPA exams (for accounting). In any case, the room was mostly empty, so it wasn’t a distraction. Even if the room had been full, the desks all had partitions, and there were even some big, chunky headphones that I probably could have just worn to block out noise (probably for the tests that have audio components).