How get email account settings from my Macbook Air onto my iPhone 5s?
On your 5s, go to Settings > Mail, Contacts, Calendars. Tap the email account, and make sure the Mail slider is on.

If the email account does not appear there, you have two options:

Add it using the email and password. More info can be found here:
https://support.apple.com/en-us/HT201320
https://support.apple.com/en-us/HT201855

Or, provide additional info on the type of email account you're trying to use on both your Mac and iOS device for further troubleshooting, eg is it a POP, IMAP or Exchange account? If you are unsure, check it here:

https://ssl.apple.com/support/mail-settings-lookup/