You can browse all the Notezilla sticky notes created using the Notes Browser.
Right click on Notezilla icon and choose Notes Browser. Then go to "All" filter. It will list all your sticky notes.
To know more about how the Notes Browser and memo boards work, watch this short video:
It is not possible to view all Notezilla sticky notes on desktop. You can place sticky notes belonging to a specific memoboard or tag on the Windows desktop. Just right click on Notezilla icon (next to the clock) and choose Desktop notes / Show notes by / Memoboard / Tag from the menu.