Lets discuss how to create new top-level directories for your theme and to copy files to those directories.
The top-level directories you’ll need are:
[your Magento install dir]/app/design/frontend/cartown/customtheme [your Magento install dir]/skin/frontend/cartown/customtheme
To create those directories and to add your theme configuration:
Using a command shell, log in to your Magento host as a user with privileges to write to the web server docroot. (Typically, this is the web server user.)
Enter the following commands in the order shown:
cd [your Magento install dir] mkdir -p app/design/frontend/cartown/customtheme mkdir -p skin/frontend/cartown/customtheme