How to interact with products cart page using shopify custom App?

hello i have created app using PHP + Laravel/React JS,

use Shopify create PHP (for create new custom app) command,

now I have created one file in resources/js/react/components/customapp/myapp.jsx,

myapp.jsf is my app file, and call it to App.jsx file

in this file I have code one HTML form using reactjs,

now I want that HTML form to interact with Shopify storefront cart page,

means like if I have submit that HTML form then its data should display on the store front’s cart page,

Like This Kind Of Functionality, I want to develop in Shopify App: Link

but I don’t know how to do that.

please guide me on this, how can we connect custom app with storefront?

hello developers,

please provide me some way that how can I do this?