Please see the installation instructions – http://wordpress.org/extend/plugins/wp-order-cart/installation/ and let me know if there is a specific part you are having trouble with.
Thank you for the answer. I believe I followed all of them and still its not working. BUT maybe i dont understand point no 8 correctly:
“To add product categories to your website navigation menu go to ‘Appearance – Menus’, ensure ‘Products’ and ‘Product Categories’ are checked under ‘Screen Options’ and drag and drop as required”
When I click screen options, I dont get any choises.. what am I doing wrong?
If you go to yourwebsite/wp-admin/nav-menus.php or Appearance -> Menus and click on Screen Options there should be some choices available – under ‘Show on screen’ should be Products and Product Categories among others like Tags, Posts, Pages etc.
What version of WordPress are you using?
And do you have a custom menu defined and selected?