Since the 4/10 security issues, I have not been able to get email on my iphone. How do I fix it?

I went online on my computer and changed my password but don't know how what to do with my iphone so I can get my email again.

Email from what ISP? If it is your iCloud account, then go to the "settings" control panel, the "Mail, Contacts" section. Pick the account in there you changed the password for and enter the new one and save it.