If you don't know what a browser cookie is, just click back on your browser and continue with what you were doing.
What the account preferences let you do is customize cool things like the number of articles to display on the main page or the way you want to view discussions.
If you know what a cookie is but you don't accept them, get real, turn them back on, and sign up for an account. If you don't turn them on and get an account anyway you're wasting your time because all the preferences you can set are cookie based.
If you're paranoid about what's in the cookie, don't worry, it's encrypted before it's sent to your computer.
