The tour starts in front of the Sweet Chick restaurant in Williamsburg, Brooklyn. The address is 164 Bedford Avenue - one block from the Bedford Ave subway station on the subway line L (just one stop from Manhattan).
The tour ends near the Brooklyn Bridge. After the tour, I usually bring my guests to the subway station that works best for them (there are several subway lines close to the end point of the tour) or to the entrance of the Brooklyn Bridge walkway, if they want to walk the Brooklyn Bridge, or Dumbo.