Just in case somebody has the wrong end of the stick, the problem could just be old Mr. Register Globals, and you want to change your piece of script to:
print 'Well, hello ' . $_GET['person'] . ', nice to meet you!';
All variables from the url string live in the $_GET array, and later you'll find all about $POST, $COOKIE and $_SESSION, but by that time you'll probably be 1/2 way to being pretty good.