Facebook smiley icons can be simple ":)" icons, but others involve symbols that require a special character combination to be typed in before they can be created. These symbols are not just specific to Facebook because they use ALT code combinations to create them and thus can by typed in to just about any program or application that accepts ALT code input. There are two types of smiley icons that you can type in on Facebook, and both only require two keys each.
Log in to Facebook.
Click in the text field where you want to create your smiley icon, such as in a Wall post on a friend's Wall, in a status update or in a comment on a friend's status update.
Press "ALT" and the "1" on your computer's keyboard -- you must use the number pad for the numbers -- for a white smiley or "ALT" and the "2" for a black smiley.