[ozrien]

Thomas's example demonstrates how to send and receive CAN frames (nice job!). What goes into and out of the frames depends on what CAN device you want to talk to. Wpilib uses this to implement support for ...
CAN Talon SRX
CAN Jaguar
...but you can write your own logic to support other CAN devices (As long as they are legal).

Did you have something specific in mind?

Also if you're just trying to get more analog channels easily, you can wire to the analog input of the Talon SRX and grab its decoded analog value over CAN bus. See software reference manual for details.