Hello
Please update the theme to the latest version and check issue.
http://themeforest.net/item/classico-responsive-woocommerce-wordpress-theme/11024192
Before update delete “woocommerce” folder in the directory wp-content/themes/classico/ and it’ll be reuploaded from a new theme package.
Don’t forget to make backup of the site before update.
To change the “Description” read this article
https://docs.woocommerce.com/document/editing-product-data-tabs/
Regards,
Rose Tyler.