Tutorial on Tokyo's trains

Tokyo runs on trains. It is a fact. It is a fact that I haven't liked much. When we first came down to Tokyo during language school in 2000 it was one of the things that made me decide I could never live here. Haha! 
I grew up in an Australian country town. I don't think I'd been on more than a dozen trips on local public transport before I went to university. I've come a long way since I was 17, but not so far that I'm comfortable with this:

This diagram shows only a handful of the lines - the subway ones. There are many more!

I knew that sooner or later I'd have to figure out how to get from one side of the city to the other on my own (i.e. without my husband who is much more competent and who's usually supported me in the past on such expeditions). The reason being that our house is on the opposite side of Tokyo to our mission's Japan headquarters. The place where many events happen. Particularly the monthly prayer meeting that I'm now going too, now that all my children are at school. My husband is 'in school' too, so I'm on my own.

Today I caught a ride to the meeting, but had to come home on the trains. Thankfully a colleague who lives close by was also coming back at the same time. So, I had a 1 1/2 hour tutorial on the route! I think I might have to do it alone sometime soon so that I don't forget. Gulp! Thankfully Japanese are usually quite helpful to lost foreigners.