Typical Plugin Structure
Generally speaking WordPress plugins are located at /wp-content/plugins/ they are not typically installed within the /wp-content/themes/… directory tree. If your theme is installing the plugin (wp e-commerce) under it’s own directory then you’ll need to work with your theme provider to work out how to update/upgrade.
For a typical install of WP e-commerce with Gold Cart your structure would be:
-
/wp-content
— /plugins
— gold_cart_plugin
— wp-e-commerce
To upgrade or install any of the plugins you’d use the standard WordPress method of updating from the repository or uploading a zip file. All within the ‘Plugins’ admin menu.
Gold Cart
The issue that you’re having with the Gold Cart installation may well be a result of memory settings within your php.ini file. The white screen is often the result of PHP simply running out of memory when trying to process a request.
Troubleshooting should start with checking your error logs and depending upon your hosting environment you may need to contact your provider for assistance.
WP e-commerce Theme Files
WP e-commerce provides for customizing the theme and functionality by copying some files to a theme’s directory. These are not the core plugin files, they are the files that control the layout and style of your store so that if fits within the theme’s design.
From there you can modify the files in a safe way; if you upgrade the plugin the upgrade will not overwrite you customizations. If you’re seeing WP e-commerce files within you theme’s directory more than likely the theme is using this method.
Before upgrading WP e-commerce I’d check with the theme provider to make sure that the theme supports the version that you are upgrading to. Only they can tell you.