Create a directory /home/shared accessible to everyone:
sudo mkdir /home/shared
Change owner of the directory, assume name of the user is alice:
sudo chown -R alice:alice /home/shared
Change access rights with read-only access:
sudo chmod -R 744 /home/shared
or with read-execute access to everybody:
sudo chmod -R 755 /home/shared
or with read-write access to everybody:
sudo chmod -R 766 /home/shared
or even make full-access directory including executable rights:
sudo chmod -R 777 /home/shared
Next everyone can add a bookmark for the directory /home/shared to Nautilus by pressing Ctrl+D.
More about Nautilus bookmarks: