i am trying to update and keeping getting error message unable to verify

See this guide:--> Get help with over-the-air iOS updates – Apple Support

If you still can't update, do it connecting your device to a computer:--> Update your iPhone, iPad, or iPod touch – Apple Support

at section: Update your device using your computer

If you don't have a computer, borrow one from your friends, or ask for help at an Apple Store or AASP:--> Apple – Location Selector

Regards

Giulio