You can find all of your existing notes on the navigation bar on the left. These notes are currently read-only because they ...

You can find all of your existing notes on the navigation bar on the left. These notes are currently read-only because they have not yet been upgraded to the new file format for OneNote 2007. You will need to upgrade your notes to edit them.  Files created with the new file format can only be opened in OneNote 2007. Take care when upgrading notes that are shared between multiple people or multiple computers. Everyone and every computer will need to be using the same version of OneNote to continue accessing them.  Do you want OneNote to upgrade all of your existing notes now? If you click "No", you can upgrade them later by clicking the information bar at the top of any page.