All it takes is to write a correctly annotated GraphQL schema file. The server uses the schema.graphql file by default which shows a few possible use cases. To start the server, type the following in your console from the project root:
go run main.go serve
You can then open GraphQL Playground from your browser and explore the API.
Next, try changing the schema.graphql file and restart the server. If you encounter any problems please let me know.