I am hosting my website with a different host, but they said I need to contact the company with whom I registered my domain...which would be Yahoo. How do I rename my current name servers to new ones?

If you want to change your name servers, go to webhosting.yahoo.com, sign in with your small business yahoo id and password, once signed in, click on small business home and look for your domain control panel, under your domain control panel click on manage advanced DNS settings, click on that, once clicked scroll down to the bottom and you will see your DNS servers at the bottom, you have to unlock your domain first.