As far as I know, you run GRIP on either your DS PC, your roboRIO, or a secondary processor such as a Raspberry Pi. The webcam is fed in as just a normal webcam ("Add Webcam"), and the data can be fed out to NetworkTables using a block in GRIP (i.e. Publish ContoursReport). See
this example from WPILib screensteps to see how to use the data in your robot code.