I would say start with Scratch (https://scratch.mit.edu/)

I have tried to teach my kids "programming" but it isn't until they are invested for their own reasons that they really care to learn this stuff. We let my oldest just look around at projects on scratch so he could find things HE was interested in (minecraft, gravity falls, etc) and then he was interested enough to start copying and manipulating projects (we didn't even show him how to do it, he just figured it out). Now he has posted his own first project and had the unique feeling of "shipping" something. I think that "shipping" feeling is the quick feedback kids need to get and stay engaged.