Amazon SP-API Seller Central Integration

We are looking for help setting up an Amazon sp-api internal application. Specifically, the project requires: - Understandable English explanations to explain what is done on each line with a clean and simple coding with PHP. - Establishment of SP-API connections - Creating a MySQL database with tables with the same name with the data coming from the API, - Parametric connection to amazon seller central store with PHP form (Multiple stores can be connected) - Selecting the relevant store on the form and seeing the relevant data of that store - Example of importing the data from the store to the local database using the Orders&Products&Messaging APIs and listing, editing, updating and deleting the data in the form with php We've already gone through the IAM Role Creation and Amazon app approval process. We have Access Key ID, Secret Access Key, LWA credentials, application number and a line of code that starts with ATZR.