Instructions
Double-click on your Internet browser icon with the left-hand mouse button.
Click on the address bar at the top of the browser and type in the address for Xbox Gamertag. Press "Enter" on your keyboard to go to the site (see Resources).
Click on the "Search" bar on the page and type in the gamertag for which you are looking. Press "Enter" on your keyboard to bring up the gamertag.
Scroll down the page to see information on the gamertag, such as when they were last online, what their "gamerscore" is and what games they've played on their Xbox 360.