How to make dropbox sync

From the Dropbox help:

1.Stop Dropbox on the PC

2. In a termina write: 

1. sudo chown "$USER" "$HOME"
   sudo chown -R "$USER" ~/Dropbox ~/.dropbox
   sudo chattr -R -i ~/Dropbox
   sudo chmod -R u+rw ~/Dropbox ~/.dropbox

   
   where Dropbox is the name of your dropbox folder 

3. Restart Dropbox