Another great resource for getting started is https://gobyexample.com/.

Also check out usage examples on Sourcegraph (disclaimer: I'm the CTO). We sell our tool to companies to use on their private code, but a side effect is that we've indexed usage examples for just about every popular Go open-source library. For example,

- Go std lib http package: https://sourcegraph.com/github.com/golang/go@bb41b4d599f5758...

- Popular gorilla/mux routing library: https://sourcegraph.com/github.com/gorilla/mux@34bf6dc9faa08...

- Gorp, a popular ORM-ish library: https://sourcegraph.com/github.com/go-gorp/gorp@033bf796a22f...

Cross-repo jump-to-def + find-references = great for making sense of new code.