New User Registration problem

Hi,

I recently bought a domain from wordpress and have been getting emails all morning about new users registrating. I understand that this is often spam and you can go to your settings and turn it off or whatever, but when I am on my dashboard and I go to general settings there is nothing about membership. I am beginning to get worried as I don’t know whether or not this “membership” is set to subscriber or not because I can’t see it!

My site is less than 24 hours old and I am getting really frusterated with it. Please help!