It’s definitely a process and if you don’t feel comfortable doing it, you may want to hire somebody who is.
With that said, the quick instructions are:
1. Hopefully you have access via your web host to a tool like PHPMyAdmin. If so, you would go into your database, export all of the database tables and download them to your computer.
2. Open the sql dump in a basic text editor and do a find and replace for all instances of https://yourdomain.com with https://yourdomain.com.
3. Once complete, you could create a new database using MySQL and upload all of these new edited tables to that fresh database.
4. You would then change your wp-config.php file within WordPress, pointing WordPress to this new database.
5. That should be it.
This instruction goes through the process of creating a separate database rather than overwriting the old, just in case you have any problems, you could also revert WordPress back to the old database since it would be unchanged.
Hope this helps, I did a quick search and couldn’t find any documentation to a better written tutorial I could direct you to. Maybe we will write one in the future.