Re: how to change a background, colors, CSS, …….?
There is apparently some issue with the install or something as it is not getting your .css file. If you try to visit the .css url you get an internal server error:
I am not sure what the easiest way is to fix this but I would uninstall and reinstall it again making sure all the stuff in the config.php file is accurate.
Someone else may have a easier solution.
Hope this helps.