When TeX and Ghostscript are in the right place, you finish the installation by unpacking the PP3 ZIP file and copying its content in the proper directories:
pp3.exeto an arbitrary directory that is in your
PP3DATAto this directory.
For the sake of simplicity, I recommend to copy everything to
C:\Programs\pp3 and to set your
PATH environment variable
and to set the
PP3DATA environment variable to
C:\Programs\pp3. That's it.