If you are re-using an old card and need to format it as FAT, then use your operating system's tool for formatting removeable media.
You can also use the SD Association's Formatting Tool, which is available for Mac and Windows and can be downloaded from here: https://www.sdcard.org/downloads/formatter_4/
You can find out more about NOOBS here.
About the Author.
As well as contributing lots of tutorials about Raspberry Pi, Arduino and now BeagleBone Black, Simon Monk writes books about open source hardware. You will find his books for sale here at Adafruit.
His latest book: "The Raspberry Pi Cookbook" is out December 2013.