How to use Amazon Cognito with DynamoDB in a Node application

I wanted to get to know AWS services in practice since I pass my cloud practitioner exam. I built a simple app on Node, and I implemented authentication with Amazon Cognito.

However now I want to save the data that the user saves in the app, related with his user in the database. I haven´t even created the table Users. In fact I have no idea what should I do tbh. I have looked through the docs but I can´t seem to find any help with particularly this.

Any idea would be appreciated. My intention is to build the backend in aws. Using API Gateway, DynamoDB and Amazon Cognito (this one I already implemented it but I don´t know how is supposed to be connected logically with the DynamoDB tables)