Does anybody know where I could learn Gatsby JS?

Last couple of weeks I have been learning about Gatsby JS after I saw a post about it here. I went through the documentation and I understood how Gatsby works. But when I saw the showcase examples in their website I came to know the capability Gatsby JS has.I have searched online but could not find a tutorial or documentation of how to build a website like those showcased examples using Gatsby JS. Does anybody have any resources on how I can build websites like the ones showcased in the Gatsby Website?