How do I backup my phone

Unless you are able to successfully enter the device passcode - this being necessary to unlock the encrypted filesystem - it is simply too late to create a backup.

If you are able to successfully interact with the iPhone - and enter your Passcode - you can backup the device:

How to back up your iPhone, iPad, and iPod touch - Apple Support

Hello pepper6262,here is some information of iPhone backup,check it out.

How to back up your iPhone, iPad, and iPod touch - Apple Support