passing parameter to my template

I would like to pass a parameter to my template, maybe something like a city name something like this:

http:\\myhappysite.com\mypagename?city=seattle

i have added the following to my functions.php so i have a recognized variable

add_filter(‘query_vars’, ‘parameter_queryvars’ );
function parameter_queryvars( $qvars ){
$qvars[] = ‘city’;
return $qvars;
}

I am missing the final step of getting the passed parameter in my template and use it.