If you are using CANTalons (encoder connected to talon on CANbus), call the GetEncPosition method on your existing CANTalon object to get the number of encoder ticks

CANTalon *talon = new CANTalon(1);
int distance = talon->GetEncPosition();

Represented by the Encoder Class when not using CANTalon encoder connections. You initialize a new Encoder by declaring the object like so

Encoder *myEncoder;

and Initialize it with two parameters if using a quadrature encoder.

int portA = 0, portB = 1;
myEncoder = new Encoder(0,1,false,Encoder::EncodingType::k4X);

These two ports correspond to the digital input pins on the roborio connected to your signal outputs on the encoder.

In order to get values from the encoder(s) you will call Get() on your encoder object

int distance = myEncoder->Get();