How to Download Modify Build and Install a Debian Source Package of Python Application

1)
Download the source and packaging script
#sudo apt-get source python-heatclient

2)
Extract the source and packaging script

3)
Modify the source ad packaging script

4)
Build the package again
#dpkg-buildpackage -b

5)
Show how to create new folder and config file like "/etc/projectname/projectconfig.conf" while installing a package. We should specify this while creating the package.