From description to story
Question: Okay, firstly, I'm sorry if this is a stupid question (I'm only thirteen and started reading this today), but I started the first chapter explaining the setting in a subtle way, but then, the part that staggers me, I don't really know how to transfer it from a description to an action. It's in third person omniscient view, and I was explaining what goes on in a library. Then I added the main character (twelve-year-old girl who loves to read). And, also, this is a fantasy in medieval-type times... if any of this information about the story is needed. Is this a common problem or stupidity? If it's stupidity, I apologize.
The important thing in an opening is to hook the reader into the story. Usually this is done by presenting an interesting narrative voice or character or a dramatic situation.
If your description of the setting fits the bill (that is, you present it in an interesting way), then you might consider a process of "zooming in and out" to get the story started.
What I mean by this is that you start from a more or less omniscient or bird's eye perspective, describing the setting. Then you zoom in a little to the library. Then you zoom in a little more to focus on the girl - what she's thinking and doing.
Once you're firmly in her point-of-view, you should stay there. However, you can have her focus zoom out a little. For instance, perhaps you start with her focused inwardly, on her thoughts and feelings at that moment. Then you can have her attention shift to some event that begins to happens in the world around her. Perhaps she goes to investigate, or is summoned, etc.
After that, you should be pretty much into the story.
Of course, you want that opening description to be intriguing and charming rather than an info dump, so you may need to keep it brief. A few unanswered questions wouldn't hurt, so that the reader wants to keep reading to get the answers.
Best of luck.