How to use my iPhone 11?

This is a massive topic, and far beyond what can be posted, and what's of interest varies widely by user and local requirements.

Start with the iPhone User Guide book that's available in Apple books:

https://books.apple.com/us/book/iphone-user-guide/id1567104665

You'll be learning about iPhone and the particular features and about the apps for the foreseeable future, too. We all will be.

This should get you started:

iPhone User Guide - Apple Support

Also, you can open the Books app and search for “iPhone 11” and “iOS” and find some free books to read on your new iPhone. The Tips app on your iPhone will have a lot of useful information.

Be sure to update your iPhone to the latest system version: Settings > General > Software Update