### install pip first ###
### pip is package manager for python ###

sudo apt-get install python-pip

### install virtualenv from pip ###
pip install virtualenv

### create your virtual environment ###

virtaulenv my_virtual_env

### activate your virtualenv ###
source my_virtual_env/bin/activate

### you can add any libraries using pip now in your my_virtual_env###

### to deactivate ###
deactivate my_virtual_env