If you were using OneNote 2016 and have existing notebooks, chances are they are stored locally on your laptop. You can use the instructions below to transfer them to the cloud to make use of OneNote for office 365
Unless you've moved them or selected a different default save location, Notebooks should be located in the folder C:\YourUsername\Documents (replacing "YourUsername" with your actual username), in a subfolder named "OneNote Notebooks".
You can Open OneNote, select the file tab in the top-left, select "open", then click the browse button on the left. Navigate to the file path mentioned, then find the notebooks you want to open. Double click on them to open in OneNote.
After opening, press the file tab again, then click on settings next to the notebook you've just added.
Click share or move, then choose the OneDrive option under your smithbucklin account.
You'll receive the message below once synced:
You can repeat this process for any other notebooks you want to sync online.