make distto build distributions of the plugin that you can upload to a Mattermost server for testing.
make check-styleto check the style for the whole plugin.
/serverdirectory, you will find the Go files that make up the server-side of the plugin. Within there, build the plugin like you would any other Go application.
/webappdirectory, you will find the JS and React files that make up the client-side of the plugin. Within there, modify files and components as necessary. Test your syntax by running
npm run build.