Welcome
CanadianMinnow, you will enjoy SH4.
I first started the game back in December of 2007. I had no prior knowledge of any sim game, especially submarines. I was pretty frustrated when I first began playing SH4. Eventually I learned how to play.
Then only suggestions I can pass to you is start with a very low % of realism. You set your realism before you leave port while you are at the desk. Then as you feel more comfortable, turn on certain realism settings and try them out. Work your way up to trying out some of the great mods for the game.
Make sure you come back to ask questions, as that's what we've all done.