WordPress.org

1. Unzip into your /wp-content/themes/ directory. If you're uploading it make sure to upload the top-level folder. Don't just upload all the php files and put them in /wp-content/themes/.
2. Activate the plugin through the 'Appearance' menu in WordPress

For upgrading please use check our website http://www.shopperpress.com/ If you have to upgrade manually simply repeat the installation steps.