What is ham radio?  For a great summary see the American Radio Relay League (ARRL) has a great summary

To become a licensed Amateur Radio Operator (ham), you need to take a test that ensures you know the basics of radio and the operating rules.  The license structure is currently broken down into 3 operating classes with increasing privileges. You must pass each test to advance to the next level.

Technician: entry level operating license that allows operation on frequencies above 50 MHz with limited output power.  The test includes questions on basic electronics and radio theory,  safety, and operating rules

General: intermediate level operating license that allows operation on all amateur radio bands with higher power limits.  Some frequencies within the bands are still off limits (see Extra below).  The test includes more advanced electronic theory, safety including issues with the higher power limits, operating rules, and the ability to receive and interpret Morse code at a speed of 5 words per minute.

Extra: top most license level with full operating privileges.  This license gives access to all available amateur frequencies and modes.  The test involves advanced electronic and radio theory, safety issues, operating rules, and testing procedures.  

Amateur radio testing is now performed by volunteer testers.  The tests are multiple choice with questions taken from a publicly available "pool" of questions.  For example, the Technician test will have 35 questions randomly choose from a pool of about 300 questions. You must get at least 26 questions correct (74%) to pass the test.  There is a small charge (about $10) for each exam session. 

Test are conducted in many locations on almost every day of the week.   Click here for the  Atlanta area exam locations and schedules

Rules

How to get started

The best way to learn about ham radio is by doing it. Get a Technician licensing study book from Radio Shack, the ARRL, book store or your public library and get the technician license.  Then get on the air and talk to others.  

There are many opinions on this, but one suggestion is to buy as your  first radio a 2 meter FM Handheld Transceiver (HT). This is a self contained unit with a small "rubber ducky" antenna.  It will allow access to repeaters in most areas.  For use in a vehicle, it can be connected to a power socket (cigarette lighter) and an external antenna. As you get more familiar with the hobby, other equipment will follow.