Short answer:
Pick up some good books on Japanese. Rosetta stone is decent, but very rigid. Keep at it, and you'll be helping others with Japanese, as you progress with your own.
Long answer:
Machine Translation is best left to Computer Science and Linguistics, NOT for language learning.
Language is living and changing. MT needs PEOPLE to TEACH it. If you can't teach said engine, it's hopeless (and comic!).
With the Turing Test aside, a machine does not have the capability to pick up on nuances and sublties, as well as typos and mistakes in an original text LIKE A HUMAN DOES.
Quick Example: ???. A machine can't research like a human. Whatsmore, many times a Source Sentence just WILL not make sense in the Target Langauge with it's structure. So, HUMANS have the ability to REWORD and UNDERSTAND the CONTEXT of a text, or the tone and sense of a joke or wordplay. (Not to mention phonemimes or phsychomimes...)
Best of luck on your studies,