It’s not hard to find them, it’s just hard getting back.
First, go into a graveyard. Start from the stone that’s furthest north, and count to thirteen in whatever direction the wind is blowing. (That’s the only tricky part – the wind changes, even with the dead.) Look for the chalk mark on the top of the last one. Check it against the legend: it’ll tell you where to go.
When you get there, knock twice. Tell them a secret. Absolutely do not lie. Seriously.
Then the games start. Remember: bring your wits, a good pair of shoes, and nothing else.