Quite a few of you are on this LJ map already (enter your own username to see how many of your friends are). Those of you who aren't:
Accept the default options on the first screen and go to the map. Don't use the world map; click on a tab at its top to get a map of your part of the world. Then enter the city you live in or one close to you in the box which appears and you'll get a more detailed map of that area. If you like, you can then zoom in 2x or 4x. Click on where you live.
If you get it wrong, you can do do it again.