There's a big difference between having a domain and having a website.
A domain is just a name, an address. A website is a place, which you build up using tools to publish text and add-ons, images, music, videos, etc.
To get a website you must have a host, like yahoo, or others on the net. And you do not need to buy a domain for it, because you get a domain name with it. But say you have a forum with another server and you want to have a personal address for that forum instead of using the servers. You then buy a domain and point it at the address your forum host gave you.
When you create your web hosting account you get all this and can log into your account to manage your web site, publish etc.
Just having a domain name does not give you the tools to do any building or publishing etc. Go to http://smallbusiness.yahoo.com or call yahoo customer support and service and set up web hosting account.
