Be sure to take a look at the [FRC 2014] PID Tutorial found with other Training Material and Resources here.
As far as working code, a good one place to start is with a working example. I would recommend going to the NI Example Finder (in LabVIEW go to Help>>>Find Examples...), search for PID and take a look at "General Auto PID Simulator.vi". This and others should lead you in the right direction.
Note also that in LabVIEW FRC, only a subset of the PID VI's from the PID and Fuzzy Logic Tookit are available.
Ryan C.
Applications Engineer
National Instruments