So, let's go over some of the basic storage details. Let's start with notebooks. They appear along the left edge of your page, in what's called the 'Navigation Bar' (or NavBar for short), as pictured below.
The NavBar can be expanded to see the sections contained within the notebooks. Some people like to keep the NavBar open all the time, however that reduces the amount of real estate you have available to you on your page, so it's really up to you to decide how you like to work with the NavBar.
Note that in Windows Explorer:
A notebook can be local, (meaning it's stored on your own personal computer and available only to you), or it can be shared, (meaning that other people can open the same notebook and add/contribute content at the same time that you are). One of the most compelling uses of notebooks is the ability to share them with others. Here on the OneNote team, for example, we use a shared notebook to discuss our priorities in our weekly team meeting. We all sit around a table in a conference room and, during our meeting, go over items that need to be discussed. At any time any member of the team can add some notes to the notebook and within a few seconds we all see those notes appear on our own screens.
I use this same feature to sync my notes on my laptop to my notes on my home computer. I can add notes to my notebook on my laptop and when I get home they automatically sync up with my notebook at home. I don’t have to do anything special, it just works. Likewise, if I add notes on my notebook at home, boom, it syncs with my laptop so I always have my latest notes with me, wherever I go.
In the picture above, you'll notice the little green synchronize icon next to the notebook. This indicates that the notebook is being shared. The checkmark in the icon indicates that the notebook is up to date with the latest changes. The synchronization takes place automatically, so you don't need to do anything special, other than open/create a notebook outside your default notebook location. If you wish to see the details of the synchronization, you can do so by opening the Shared Notebook Synchronization window. To do this click File -> Sync -> Notebook Sync Status. This allows you to change the online status of a notebook, see the synchronization progress, or check for sync errors.
Sharing a notebook is easy. You can do it one of 2 ways: