mods-for-frisco-custom-bg.php

<?php 
add_filter("bppg_iwilldo_it_myself","__return_true");//stop the plugin to inject css

//now we can write our own css

add_action("wp_head","my_css_for_profile_bg");

function my_css_for_profile_bg(){
$image_url=bppg_get_image();
if(!$image_url)
return;//this user has not uploaded an image yet
?>
<style type="text/css">
body.is-user-profile div#container #content .padder{
background:url(<?php echo $image_url;?>) no-repeat;/*please customize it*/
background-size:100%; 
}
</style>
<?php
}
?>