Aftk is spot on.
A couple of other things.
From previous experience, he’ll keep it clean.
Dogs mouths are full of bacteria, stop him from licking it. Their tongues are also very rough and he will wear the skin away.
Generally leave it to the air, but give it a bathe in some warm water once in while.
While its healing only walk him on hard surfaces, mud, sand or grit can get into the wound, heal over and you’ll end up with a very bad infection.
For me, whenever Rickon does this (my dog, hence my name), I rest him at hone for a couple of days. He’s grumpy and sulks, but he’s better in a few days.
Keep it dry, keep it clean.
And if there’s a flap hanging off, and he’s good with you touching his feet, cut the skin off. Its dead, and it could rip more skin off if he catches it.