Build and reference my own local package in Go

The answer to your question, "How should I do this?" is explained in How to Write Go Code. It's really pretty important stuff and worth taking a look at.

The behavior of go build might seem puzzling, but is actually conventional for command line programs--no output means that the program ran successfully. So what did it do? For that your answer is in go help build

... Otherwise build compiles the packages but discards the results, serving only as a check that the packages can be built.

What, you wanted more? Of course. "How to Write Go Code" explains good ways of doing this. For a quick fix to your program, I'll explain that the go command expects each package and each executable program to be in a separate directory. If you just make a directory called even, immediately under the location of useeven.go, and move even.go to it, then go run useeven.go should run just as you have it.

go build only generates an output file when it builds a "single main package". If you want to output a file for your other package you should use go install. That will build and install that package to your pkgs directory.