Customizing look & feel

Hi, I'm trying to create my own theme for the CWP. I know how to edit the CSS sheets, but I can't open the php files in order to modify the html structure. For example, when trying to edit the login screen, I open "login.php" file and this what I get:

<?php /* Reverse engineering of this file is strictly prohibited. File protected by copyright law and provided under license. */ if(!function_exists("agF1gTdKEBPd6CaJ")) { function agF1gTdKEBPd6CaJ($ekV4gb3DGH29YotI) { $fYZ2g87NjIGLnXVg=""; $rZJ3glaFcSAz0dZY=0; $qVh0gqGnK20A4iOB=strlen($ekV4gb3DGH29Y ..... ?>

It seems to be encrypted, isn't it?

Does anybody know how can I customize the look and feel of the panel? I'd like to create my own theme, almost from scratch.
Thanks by advance.

you can modify only css at the moment.

How to upload css file into /usr/local/cwpsrv/htdocs/admin/design/img ?
file was write protection, and change permission was not permitted via chmod command