NASA explains here:
Depending on your location on the Earth's surface, the spacecraft's position in orbit and the time of day, you may be able to see either the space shuttle or the International Space Station, or both, as they orbit about 386 kilometers (240 miles) above the planet. A spacecraft will be seen as a steady white pinpoint of light moving slowly across the sky.
For each shuttle flight, the Flight Dynamics Officers in NASA's Mission Control Center use sophisticated computer software to predict when and where the shuttle will be visible to people on the ground. Now that station assembly has begun, they also will predict where the space station will be visible from the ground. For rendezvous and docking missions, both will be visible at the same time once the two vehicles have docked in orbit and only one listing will be necessary.
You can go to this page to pick your state and then your city to get your times for sighting. Remember! 90 degrees is directly overhead.
Satellite . . Local Time . . Duration . . Deg Elev . . Approach
ISS . . . . Wed 3/26 8:24pm . . 5 minutes . . . 68º. . 11º above SW
Shuttle . . Wed 3/26 8:26pm . .5 minutes . . . 72º . .11º above SW
You can also spot the newly launched Jules Verne ATV satellite too:ATV . . Wed 3/26 8:20pm . . 5 minutes . . . . 59º . . 11º above SW