Ask HN: How should I teach code to kids?

My little cousins are 7 and 9 years old. I have been thinking a lot how can I get them started with building and designing for the web.

I just finish my first attempt https://www.youtube.com/watch?v=BiwWT2CERA8

I wanted to ask the HN, what other ideas or what type curriculum I can do to make it more fun and interesting for them. All ideas are welcomed.