To be successful you have to follow the instructions more carefully.
People will stop helping you if you don't take more care in future.
C:\Program Files\KonaKart\custom\bin>ant -p
Buildfile: build.xml does not exist!
Well, that's because you're in the wrong place.
Think about it and look carefully. The error message is pretty useful.
Move to the custom directory one level above.
Moving the build.xml file is not a good idea.
Why don't you just follow the documentation (and my earlier post) carefully and issue:
C:\Program Files\KonaKart\custom>.\bin\ant make_liferay_portlet_war