No module named ROOT (GNU/Linux)

I faced same problem. I just tried to install PyROOT and I am a newcomer to it. I edit my ~/.bashrc file and add $PYTHONPATH to /home/rik/root/bindings/pyroot/ROOT.py (location of ROOT.py) and got same error. Can anyone help me how to overcome this?
Also, please guide me how to enabled PyROOT properly with ROOT?

I just follow these procedures but got error.