Help with putting Adsense in php code. Please help

hello
I just bought the premuim news them and help putting my adsense code in the 300/250 box and others. I asked the creater of the theme for help, but wasnt given much but where to find the files to change. I have a very basic understanding of php and was told to start with the ad files.
where do i put the adsense code? I’ve tried in different places and it just messes up the theme.

<?php $no_show = get_option(‘premiumnews_not_mpu’); ?>

<?php if ( !$no_show ) { ?>

<?php $show_home_only = get_option(‘premiumnews_home_only’); ?>

<?php

if ( $show_home_only ) {

if ( $GLOBALS[‘home’] ) {

?>

<div id=”mpu_banner”>

<?php

// Get block code //
$block_img = get_option(‘premiumnews_block_image’);
$block_url = get_option(‘premiumnews_block_url’);

?>

href=”<?php echo “$block_url”; ?>”><img src=”<?php echo “$block_img”; ?>” alt=”” />

</div>

<?php } else { include(‘ads-top.php’); } } else { ?>

<div id=”mpu_banner”>

<?php

// Get block code //
$block_img = get_option(‘premiumnews_block_image’);
$block_url = get_option(‘premiumnews_block_url’);

?>

href=”<?php echo “$block_url”; ?>”><img src=”<?php echo “$block_img”; ?>” alt=”” />

</div>

<?php } } ?>

thanks in advance