To create a new Notebook simply go to File>New Notebook and title your new notebook. With this notebook selected you can then add New Notes with the quick add button on the top of the screen. Once you have a new note simply add content to the note and it will automatically save your added information. You can add new notes and notebooks as you see fit.
You can organize your new notes and notebooks:
The default order for notes is most recently added on top and the default view is "Snippet" view, but you can reorganize the order based on various factors and customize your view to suit your needs for that particular notebook.
Notebooks can also be grouped together, inside "stacks." For example, you could make a stack called Fall 2017 Semester and then put multiple notebooks for different classes inside. You can share notebooks, but can't share stacks. On the Mac version you can drag and drop notebooks together to make a stack; in the Evernote for Windows or Web, right click a notebook and select to add it to an existing stack or create a new one.
Another way to organize your notes is to give them tags. Under the title of each note you'll have an option to add tags to a note. You can find notes using the menu Tags in your left menu under the Notebooks you have created.