How do you teach a kid under 7 years chess?

My sister has a son he's 5 years old and i want to teach him chess because I've seen so many chess players under 7 years old and they've about like 1000 elo so I'm wondering what's the best way to teach a child chess so if someone know a child who knows how to play chess or someone who teached a kid how to play chess and can give me ways to teach a kid to play chess