First go to the Dropbox website and download the .deb package. Make sure you select the (x86) package.
Once the download is complete, double-click on it to start installation. When the installation is over you will need to restart Nautilus; you can do this by logging out and back in or by executing the following command in Terminal (Applications -> Accessories -> Terminal).
Now you will see the Dropbox icon appear in the taskbar.
Right-click on the icon and select “Start Dropbox”. This starts the downloading of Dropbox. Sit back and wait until the download is complete.
Once Dropbox has been downloaded the setup will begin. Follow the instructions on the screen and proceed.
Note: By default your Dropbox will be in the directory “YourHomeFolder/Dropbox”. If you want to choose another folder, you can tick “I want to choose where to put my Dropbbox” in this screen.
Setup is now complete and you can start uploading and sharing files!