Build Universal cart for my site

This is a possible approach to solving your problem (with more knowledge about your website and your requirements, approaches with more elaboration will be conceived): Edit the main template for the site (if it has one) so that the navigation bar has a shopping cart icon that links to a new, internal shopping cart page. Make it so that former buttons that linked to the separate shopping cart site now go to the new internal shopping cart page. As well, add function where users can add items to the shopping cart and previously mentioned shopping cart icon indicates addition with an animation showing a number representing updated amount of items in the shopping cart. Shopping Cart page - Lists products added to the cart in a table. Includes columns for image of product, cost, vendor, more details Has functions for removing a product from cart Function for changing the # of a particular product they want to order Checkout button Checkout page - Selecting method of payment (PayPal, credit/debit card, etc) Select shipping & billing addresses Back/Return button Order button Confirmation page: Lists relevant details of the processed order Button to return home for more shopping Questions: Does this website have function where users sign in and have a user account? Relevant for if user signs in after already adding items to their cart, What kind of website is this and what language is it programmed in? Is it a WordPress site, a custom PHP site?

A proposal has not yet been provided