Autofocus imageselection home.php

Hello there,

im using the autofocus theme for my page h2mo.de
my problem is that with this theme by default the last uploaded picture of a post is used for the frontpage image.

what i’d like to be able to do is selecting the image myself by adding a property to each image which says frontimage=1 (or something similar)

my php knowledge is quite limited so forgive me if there is an obvious solution to this.

home.php in this theme contains this code:

<span class="attach-post-image" style="height:300px;display:block;background:url('<?php the_post_image_url('large'); ?>') center center repeat"> </span>

refrencing to

[Code moderated as per the Forum Rules. The maximum number of lines of code that you can post in these forums is ten lines. Please use the pastebin]

so how do i manipulate the insert picture function to contain a new field and then check it within function the_post_image_url($size=large) ?

Thanks for your help.