Hi GrannySmith905,
Thank you for participating in the Apple Support Communities. It looks like you came from the following support article: Update your iPhone or iPad - Apple Support
If you are unable to add your email account, here are a few steps to try:
1. Restart your iPhone to see if the issue persists: Restart your iPhone - Apple Support
2. If you are seeing a specific error for your Yahoo email, reach out to Yahoo.
3. Try the steps here to see if they help: Add an email account to your iPhone, iPad, or iPod touch - Apple Support
4. If you need further support, reach out to Apple Support here: Contact - Official Apple Support
Have a great day.