Yazd is a desert city in Iran with 423,006 inhabitants (2006). The city is famous for being in a desert, the mosque, and the little alleys in the city's old town.
To get out of the city, ask any driver to take you to 'gate of the city' (most Iranians in cities work as freelance taxi-driver, but they don't charge too much), followed by the direction you want to go. Having a map of the city will help you very well. You can walk to one of the city gates as well but it will take you a long time - especially when you're in the center of the city. From there, the highway starts and you can start hitchhiking.