Paging

Hi everybody, I have a paging question. I have a page where you can view a persons 'profile'. And I have a list taken from the db of there books. I can get all the books on one page but I can't figure out the WHERE from the get. This is what I tried but it didn't work.
$query   = "SELECT COUNT(*) AS numrows FROM tabs WHERE user_name='".$_GET ['user_name']."';
 $data  = mysqli_query($dbc, $query) or die('Error, query failed');
 $row     = mysqli_fetch_array($data);
 $numrows = $row['numrows'];

When I do this it shows a second page but when I click on the next page It goes to my profile or the user who is logged in, not the users profile I was looking at on page 1. Thanks every one for all your help!!