To use facebook chat in pidgin enter the followig commands
1.sudo apt-get install pidgin-facebookchat
Now you should have pidgin-facebookchat-1.38.deb package.Install this .deb package using the following command
3.sudo dpkg -i pidgin-facebookchat-1.38.deb
This will complete the installation.After installation you need to restart Pidgin! You will then have a FacebookChat option in your accounts manager dialog.
screenshot of terminal is added