New iMac but not able to setup email. Where to start?

Did’t help. COSTCO ‘s concierges service was NOT helpful. Had to go to Apple support. It was a simple fix (not for me) just had to go to System Preferences and set s system preference for my email. Somehow, this step got messed up just at the start. There should have been a straight forward way in the setup procedure to account for this since it didn’t work as it should have.