Sweet DNS

Google, Microsoft and Yahoo talk about IPv6 whitelist Big names consider central record of customers capable of IPv6 access Leading web content providers, including Google, Yahoo, Netflix and Microsoft, are conducting early stage conversations about creating a shared list of customers who can access their websites via IPv6, the long anticipated upgrade to the Internet’s main [...]

I am tyring to add a spf record (in txt format) to my dns settings. My domain is hosted by yahoo. How can I do that?