Your question should be
How to install packages in Python 3?
- go to https://www.python.org/downloads/ and download Python 3.4 or newer. (This has the pip command to install packages)
- install it.
type
pip3.4 install pillow
if this does not work then use the full path (example for windows):
C:\Python34\Scripts\pip3.4 install pillow
the import statement should work now
import PIL
If you search for this you can find many answers: https://stackoverflow.com/search?q=python+install+PIL