Astronomers use star charts to locate stars and constellations. On the web, there are many places where you can download star charts based on your specific location and/or the time of year. Since the stars aren't moving very fast (with respect to the earth), you can use the same star chart for several nights (depending on the type, you may even be able to use the same one the whole year). Below are a few sites where you can download (or print) a star chart.
Constellation charts and more! This is a fantastic resource. You can load star charts of all the constellations and interesting objects therein. You can also use this page to help you learn the constellations.
Earth's City Lights is a picture created by NASA that shows the most urbanized areas of the world.
Overview with activities for younger students
Sky & Telescope's guide to getting started
Lakota Star Knowledge has an introduction to star knowledge of the Lakota people, with great maps and charts. Compare star groups to the Greek constellations we use.
Ancient astronomy around the world has very brief descriptions of astronomy from around the ancient world. The page is difficult to navigate because pages take so long to load. Perhaps the best parts of this page are the timeline and the links to other pages.