Your guide will meet you in front of Bobby's Sandwich Bar, the orange shopfront. They'll be wearing a wizard costume and an Edinburgh Guide badge. This is on the intersection of Candlemaker Row and George IV Bridge/Forrest Road and NOT inside the graveyard! This is not the "Greyfriars Bobby's" pub.
Your guide will drop you off at Victoria Street, only five minutes walk from the start point, and will be able to help you with navigation for your onward journeys.