You can either refer to the following URL or to the tutorials located on the Your Store demo.http://www.shape5.com/product_details/club_templates/your_store_-_july_2007_club_template.html
To change the color theme log into your Joomla admin side of your site. In the admin navigate to your Joomla templates from the top menu: Site > Template Manager > Site Templates. Select "yourstore" and then click "Edit HTML". Scroll down a bit and you will then see something similar to the following:
// Template Configuration
$s5_color = "color1"; // color1-10
Just change "color1" to whichever color theme you desire to use.
Let me know if you need any other help.