Inserting a variable in a link

[SkillsToShow]

I have this code that I want to insert for my own variable but I have no idea how. This is what I want to insert:

 

<?php echo $my_twitter_username; ?>

 

Into this code:

 

<?php
[i]function twittercount () { // I added this myself, not sure if I should, but if not there line below does not work
global $my_twitter_username; // Im sure this is needed or the call in will not work.[/i]
$tw = get_option("twitterfollowerscount");
if ($tw['lastcheck'] < ( mktime() - 3600 ) )
{
$xml=file_get_contents('http://twitter.com/users/show.xml?screen_name=[u][b]WANT TO INSERT HERE[/b][/u]');
if (preg_match('/followers_count>(.*)</',$xml,$match)!=0) {
$tw['count'] = $match[1];
}
$tw['lastcheck'] = mktime();
update_option("twitterfollowerscount",$tw);
}
echo $tw['count'];
}
?>

[sasa]

$xml=file_get_contents('http://twitter.com/users/show.xml?screen_name='.$my_twitter_username);

[SkillsToShow]

Thank you! It worked The only thing is that you need to remove the function line at the top.