I need help with the specific settings I need to put in DNS for dkim?  I'm using cloudflare DNS.

1) Is it a txt record or a dnskey record?

2) The directions say: "Add the public key below to the subdomain 1522905413783._domainkey.nurturechi.com in your domain's DNS settings."

What is a subdomain in DNS?  Do I put the value "1522905413783._domainkey.nurturechi.com" in a field?  What field is it?

3) what specific field do I copy paste the public key into?

Apologies, but a lot of this is new to me. :)