Blueman is the Bluetooth manager for Ubuntu. Therefore, install the package.
susanta@admin:~$ sudo apt-get install blueman
Now, go to System > Preferences > click on Bluetooth Manager
Now click the search button, if any bluetooth of handset(s) are in active status, then it will find and inform you the name of the device.
Here, the searched device name is listed. Now to pair with the device select the name and click Pair button.
Now, input the paired code and same code will be asked by the handset with which you want to pair. You should enter the same code in your handset.
To send file(s) to you paired device, just click on Send button