Microsoft has released a User Guide for Lumia with Windows 10 Mobile, introducing users to its features & to help them get started with this new mobile operating system.
User Guide for Lumia with Windows 10 Mobile
The 137 page user guide contains pretty much everything you will want to know about the Windows 10 Mobile operating system. It tells you how to power on or off your device, how to navigate, how to use the tiles and the apps, how to personalize your mobile phone, and more. It also tells you how to troubleshoot he phone should any problems arise, how to update the OS ^ apps when required and more. It touches upon all the Settings briefly and explains each one of them.
Very useful are the tips on how you can transfer content from Symbian, Android, etc., phones to your new Lumia.
Another section which users may find useful is what each of the Access Codes stand for. For instance, the IMEI is used to identify phones in the network. You may also need to give the number to your care point services or phone dealer, and to view your IMEI number, dial *#06#.
You can download the user guide in PDF format from Microsoft.