Tricky Things- Legs

I took Fabrizio out the back to kick a ball around. He was up for that, but even more interested in the big stone step between our yard and the path that runs along the back of the houses. He could get up it by himself- no problem- but getting down again was a challenge- and he had to hold my hand or he'd have fallen flat on his face. So what is the secret? What do you have to do with your legs to get safely from A (up here) to B (down there)? We practised the manoeuvre over and over and over.