Looking at your other thread, I see you are using the AS5145B Magnetic Encoders, not the US Digital E4Ps. According to
this page, these encoders output 1024 pulses per revolution, unlike the E4Ps which are only 360 pulses/revolution.
Have you looked at
this page yet? It explains how quadrature encoders work, and gives some examples of how to use the WPILib Encoder class.
The constructor call is where you create the Encoder object, usually as an instance variable of your robot class. For example, to create an Encoder with the A channel in DIO 1, the B channel in DIO 2, counting the normal direction and 4X decoding, you would use this:
Code:
Encoder myEncoder = new Encoder(1, 2, false, EncodingType.k4X);
Here's a simple example of using encoders to drive a robot in autonomous:
https://gist.github.com/DomenicP/7252269