how to start fresh and add custom backgrounds I am completely new to Drupal 7 and have searched the web hard for a good tutorial that teaches me how to add a custom background to Drupal sites, but to no avail.

I have a Drupal 7 multi-site set-up and I am just trying to change the background image of the Bartik theme to a custom image.

In my project directory I have the following folders:

mysite/files
mysite/modules
mysite/themes
mysite/tmp
mysite/settings.php
mysite/default.settings.php


Could someone please tell me a way to create a custom background, exclusively, for the site "mysite" without editing any of the core files?

Thanks.
Create a folder called "myTheme" in sites/all/themes
Create a file in that new folder called "myTheme.info" 
Copy the sample .info from below into the info file
Now create a folder in your theme called "css"
Now copy style.css from Bartik's css folder into your css folder
Now change the background using CSS
Any other changes you want to make? Copy from bartik into your theme folder, make the change


Sample info file:

name = My Theme
description = My theme is amazing
core = 7.x
engine = phptemplate
base theme = bartik