Gmail authentication

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

    host gmail-smtp-in.l.google.com [172.253.63.27]
    SMTP error from remote mail server after end of data:
    550-5.7.26 This mail has been blocked because the sender is unauthenticated.
    550-5.7.26 Gmail requires all senders to authenticate with either SPF or DKIM.
    550-5.7.26
    550-5.7.26  Authentication results:
    550-5.7.26  DKIM = did not pass
    550-5.7.26  SPF [totalhomeinc.com] with ip: [66.96.184.2] = did not pass
    550-5.7.26
    550-5.7.26  To mitigate this issue, please visit Gmail's authentication guide
    550-5.7.26 for instructions on setting up authentication:
    550 5.7.26  https://support.google.com/mail/answer/81126#authentication b7-20020ab00847000000b007c1aef33bf2si621577uaf.77 - gsmtp

@elyzabethv

It seems like you've helped a lot of people with this, but I haven't found any instructions on how to fix it myself.  Can you help?