I have been a couple of times already , “where can I go, when I am in Tokyo?”. First, it will really depend on where your interest lies. Japan Guide’s website is the very first to go to. Most major tourist destination in Tokyo or Kanto region are already listed there.
Then how to get there also depends on where you are staying, be sure to know which train station is the nearest to your hotel and check on Hyperdia for train time and fare.