Follow the in-project instructions. Sorry for any confusion that may have been caused by my saying that this is Java. I meant JavaScript and have changed the name accordingly.
https://scratchblocks.github.io for the blocks you see in the project. Super awesome. Give that place a visit sometime. Oh, and while you're at it, love, fav and follow for more cool stuff. Although, now that I think about it, half of my projects are stupid. But that's not the point. More off-topic nonsense below I wanna rickroll myself but my inner Rick Astley is like, "never gonna rickroll myself"