you can always register through Rock The Vote

 

I don't know about where you live, but where I live in Santa Clara county of CA, anyone who is registered to vote would receive a sample ballot (and a voter information booklet explaining each candidate's position and arguments for and against each proposition on the ballot) a few weeks before the election. So you may check with your county voter registration office to see if they send out such booklets. If they do and you have not received it, then you know you are not registered to vote.