Very easy.
Sign up for the free version. Download the program and install LogMeIn Free on any computer in your office that runs AC and has an internet connection. You must leave this computer, and the "main computer" that has the AC database, both turned on to run AC from outside the office. Then you simply log into logmein.com from any internet connected computer, put in your password, and connect to your office computer. Your office computer's desktop appears on your outside computer's screen, and you control it just like you were there in the office.
Even the free version has
several security features including AES 256-bit encryption.
Some fine tuning to LogMeIn is discussed
in these posts.
