If you still don't see the Login or Sign Up link, then the problem is most likely a browser in need of an update or a 3rd party Plug In (or Addon) that was poorly written and blocking. You can either try another Browesr (I use Google Chrome with no add ons or Plugins) or disable your Plugins or Add Ons until you find the offender.
To be able log in, you must first register. It only takes only a minute to do so. Click Here to Register. To complete your Registration you will have to click an activation link in an email Immediately sent to the email address you gave. If you don't see that email after ten minutes, it has to be in your Spam Box, which is a common problem.