Although it's pretty easy to get a site up these days, I don't think universities expect everybody to have their own domain with a site. I think the idea is that maybe some people have a site with their résumé or achievements on it, and perhaps they're interested in that.
If you do want to have your own space on the web, check with your undergraduate university. They may allow you to have a page on their site somewhere. Otherwise, it's the usual suspects--www.geocities.com, for example.