[module - private shop] change background and others

[teJ20]

i've punched private shop from presto-changeo[dot]com but they don't offer free support for costumization.
so i want to change the background from color (black by default) to certain image.
i've modified

$('body').append('

');
to
$('body').append('

');

but with no success.

also i want to hide the logo and here is the text 'YOU MUST BE A REGISTERED USER TO ACCESS THIS SITE.' i want to put an image.

thanks