did you try googling "moving to japan"? The first results page alone had no fewer than 8 "complete" guides to transitioning to Japan, and one post from someone else who didn't know how to use a search engine. Most of those articles are attached to entire websites for expats or people looking to move to Japan.
Since you want to go work as an English teacher and don't yet have a BA, and from your other post I'm guessing you aren't engaged to a Japanese national, you'll have plenty of time to read up on all the logistics while you work towards fulfilling the visa requirements to move to Japan. Will your fiancee be coming with you? Will he be working as well, or will he be there as a dependent?
It might help, once you sort out all the hoops you need to jump through, to set a realistic timeline for yourself, and place appropriate goals along the way to help you reach your goal. Getting to Japan as anything other than a tourist is a marathon, not a sprint; enthusiasm alone will not get you there. Also, have you had a chance to visit? Going on a vacation is a lot different from living and working there, but it's a nice way to scope out the landscape, make sure you'll actually enjoy it, maybe meet with some expats and get the benefit of their first-hand experience.