How to use gengo?

[TheFern2]

I downloaded gengo to my Ubuntu 20.04 machine, and installed as what I guess is a ros package with catkin_make. How do I use gengo to generate messages, I see comments on source files but that's not working.

fernandob@ros-vbox:/media/sf_ROS/git/rlw-go$ go:generate gengo msg caros/SignalID
go:generate: command not found