Make sure to turn off your WiFi connection or this wont work.
go to mail icon
enter email address in email address filed (email@example.com)
enter password at password field
select MANUAL SETUP not next
password = yourpassword
imap server= imap.mail.yahoo.com
optional = blank
you will then be prompted to sign in do so.
will then be taken to the smptp settings which only prompts (going form memory) you for address which is smtp.mobile.mail.yahoo.com. leave the port as is. then select next. sign in. name your account and that's it.