Welcome aboard!
As Spraug suggested, the best thing you can do right now is play in the easiest mode. It does the targeting automagically; all you have to do is make sure the little arrow is green. I mostly play SH3, and in that one they had an in-between mode, in which you had it set for Manual Targeting but your 1st Mate did all the info gathering for you, which made it easy but also made it feel real.
Unfortunately SH4 does away with that, so you're stuck with it either being very easy or very hard. My math skills are pretty much non-existent, as are my gathering skills, so after almost eight years I still play on the easy mode.
All that said, there are people here who are very good at it. Expect help soon.