Hi Dor,
There are a couple of different encoders that have come in the KOP in past years, the most common of which is the US Digital E4P Quadrature Encoder. I assume that's what you're referring to? If not, let us know.
US Digital has a page with resources related to FRC:
http://usdigital.com/first. Here you can find an assembly guide video and
PDF. Here's a link to the data sheet as well:
http://usdigital.com/assets/datashee...59032230617729
When it comes time for code, the ScreenSteps Live documentation for WPILib has a page on encoders:
http://wpilib.screenstepslive.com/s/...using-encoders