How to update my iPhone?

Assuming you have a compatible device, see: Update your iPhone, iPad, or iPod touch - Apple Support

And: If your iPhone, iPad, or iPod touch won't update - Apple Support

If the above Apple articles do not help, please post back with relevant information. 

To update your iPhone, follow these steps:

1. Connect your iPhone to a Wi-Fi network.

2. Go to the 'Settings' app on your iPhone.

3. Tap on 'General'.

4. Tap on 'Software update'.

5. If an update is available, tap 'Download and Install'.

6. Follow the on-screen instructions to complete the update.

Make sure to backup your iPhone before updating to prevent any data loss. You can do this by going to 'Settings' > 'Apple ID' > 'iCloud' > 'iCloud Backup' > 'Back Up Now'. (ALTHOUGH THIS IS UNNECESSARY).

I hope this helps!