Watch this video that answers your query perfectly:
Open the folder where the new Notezilla installation is storing its data. To know where Notezilla stores the data, go to Notezilla 's Preferences and click on the Advanced tab. To access Notezilla 's Preferences, right click on Notezilla icon and choose Preferences from the menu. Copy the whole path and open it from Windows start menu.
Exit Notezilla .
Open the backup folder from the old Notezilla . To know where Notezilla backups data, go to Notezilla 's Preferences and click on Advanced tab.
Copy Notes8.db from the backup folder to the folder you just opened in step #1. Overwrite any existing file.
Run Notezilla . That's all. You must now see all your notes.