I built a road with my second settler (I play on Emperor). I had situated my capital so that the city radius contained wheat, fish, and two other special squares that I had not yet discovered. The computer by default put a worker on a tile that generated no trade, a shielded grassland tile that produced two units of food, and one shield. When my city reached the size of two, I was prompted what technology to research, as my new worker was placed on the wheat tile that contained a road, and generated trade. Thanks guys.