What you're experiencing right now is a pretty common thing among programmers. Everything seems straightforward from a high-level overview, but when you get down to the details, they can seem overwhelming.
The lucky thing is, although it seems never-ending now, it isn't. Eventually you'll learn enough about the API or subsystem or problem domain that you're looking at to make a little progress. You'll write a line or two of code, or maybe an entire subprogram, and you'll retain what you've learned. When you move on to the next small programming task, it'll take less research, because you'll remember what you learned earlier.
Eventually, you will learn most of what you need to know about the APIs you're using. You may not necessarily remember every single function argument or command option, but you'll know the rough outline of what you can do, and you'll know where to go to look up the details when you need them.
As you progress, you'll be able to move your emphasis from reading documentation to coding and debugging and refactoring and all those other fun things. There will always be new subsystems, new libraries, new APIs to get used to, so your job will always involve a little of this sort of thing. What seems insurmountable to you now will eventually seem quite normal.
Don't worry. Nobody else was born knowing all the details. If you can just keep going until it starts to get easier, you'll do fine.
It's getting kind of dated now, but Neal Stephenson's "Mother Earth Mother Board" is great reading if you're interested in both the history and the process of laying submarine cable: http://www.wired.com/wired/archive/4.12/ffglass.html