Python bindings for PDFNetC officially supports Python 2.7.2 / 3.2.2 and higher. Older versions are not supported. So the first part of the solution would be to upgrade.
As for your issue, it seems that the Python interpreter cannot find the _PDFNetPython2.pyd. You will either need to copy both PDFNetC.dll, PDFNetPython2.py, and _PDFNetPython2.pyd where the Python is installed, or set your PATH environment variable to where these three files are located.