How can I mirror Shotwell library in the directories?

You can decide for yourself where Shotwell keeps and looks for the pictures in "Shotwell Preferences", under "Library Location". Just change the directory next to "Import photo's to:".

When you import photo's into Shotwell using Shotwell, Shotwell organizes the pictures, using a naming scheme that you can define in the "Shotwell Preferences", under "Importing".

In addition, Shotwell can be set to watch its library directory for changes done outside of Shotwell: "Shotwell Preferences", under "Library Location". Make sure "Watch library directory for new files" is checked to have Shotwell update the database according to the files present there.