Basically, you’ll need a Github account and to link the project to a repository. Next, you’ll have to convert it to JS and use Makecode’s custom code to make blocks. @shakao has made a good reply to my blur demo when I was trying to do that extension (although it was personalized to my blur extension, it can still help.) Also, there’s a page that might help with the basics, coding an extension, custom blocks, and getting it working for others to see. The playground is a very nice resource for finding out how to code an extension and allows real time testing (although after you’re done, you’ll have to paste the code into the project linked to Github.) I hope this helps and you can get your extension working!