To install the latest version of PythTB simply type in terminal:

  pip install pythtb --upgrade

If you don't have root access try installing PythTB into your home 
folder by executing:

  pip install pythtb --upgrade --user

If you don't have pip installed, consider updating your python.
Alternatively, you can follow instructions here on how to install
PythTB without pip: 

  http://www.physics.rutgers.edu/pythtb/install.html

PythTB is compatible with Python 2.7 and 3.x (Python 2.6 and 
below are not recommended).
