Don't know who hosts your DNS?

Your DNS provider isn't always the same as your domain registrar — it's wherever your domain's nameservers currently point. The fastest way to find out is to run a free NS lookup on your domain, or run the full diagnostic, which auto-detects your DNS host and shows it at the top of the report.

What you'll be pasting

Every TXT record has three parts: a host (where it lives — @ for the root, _dmarc for DMARC, google._domainkey for a DKIM selector), a type (always TXT here), and a value (the actual record content). Generate the value you need with the SPF checker or DMARC checker, then follow the guide for your DNS provider to publish it.

Email-provider setup, not DNS-provider setup?

If you're looking for the SPF include or DKIM steps for a specific mail provider (Google Workspace, Microsoft 365, Fastmail, etc.), see the mail-provider setup guides.