PHP code help. (only using HTML, CSS, and PHP code)

For a class project, I am making a website. I just need some help with this part of the assignment.

9. The website should incorporate an e-commerce solution that allows users to purchase products online. A minimum of 10 items should be listed for sale. Items should have an accurate picture, description, price, and quantity. 10. The e-commerce solution must include a checkout process where the user can add, update, and remove content from the store shopping cart. a. The shopping cart process should be simple and easy to follow. b. Users should get the total price before checking out including calculated taxes.

I already have come up with 10 products. For your answer, you can choose two items. (Just a side note I already made the website Products.php to display the products and information about them. I need to put in a code that adds the amount they want to their cart. Then, anything to do with the cart and buying them is the code I need. Like the checking out process.)

https://github.com/Razor2b/CSIS410BRINKLEY/tree/main/CMS is where my code is at if you wanna look at what I have, but what I have in the Products.php isn't working so if you come up with somethingbetter I am all for it.

THANK YOU.