Page without sidebar and content resize

Hello,

I have my page without the sidebar by making a new template, and the code are:
==================================
<?php

/*

Template Name: aFILE

*/

?>

<?php get_header(); ?>

<div class=”content”>Content</div>

<?php get_footer(); ?>
=================================
The thing is it work well which takes the sidebar away, but the page content still the same size as it was, ie the ex-sidebar still occupied the un-used space, question is how can I resize the content box which expand to the right of the webpage?? I am not too good at coding, anyone code give me the code??

Thanks!