Hmm do you mean RS classic or Runescape2? If you are trying to get on RS classic you would need an RS classic acc which can't be made anymore. They had an opening for about 2 weeks where you could make a RS classic acc but if you didn't make an account in that time you cannot play. Sorry. (You could always buy one, probably on here even)
To play RS2, if you are now you need to log in using your email. It shouldn't be hard