DNS verification

I was interested in getting an email hosted for free by zoho mail.com

When I went on the zoho site, they gave me the option to purchase a domain from "I want my name.com" so that I could have a seamless integration with the zoho mail hosting.

I purchased the domain from "I want my name.com"

In the setup with zoho mail subsequent to purchasing the domain "riverelectric.co" it requests that I verify ownership of my domain. However in the domain verification wizard/setup instructions, it requests that I choose from a dropdown to pick the DNS (domain Name server) that is hosting my domain. There are several choices in the dropdown, but the DNS/company that I bought the domain from, is not showing it's name in the choices. ("I Want My Name.com")

Can someone help me discover how to get my domain verified, so that I can then proceed to get my email "jake@riverelectric.co" operational and fully hosted by ZOHO. I don't need another website, which is what the ZOHO website seems to wish me to setup.