No code provided, I am the beginnger
Start with http://cern.ch/geant4-userdoc/UsersGuides/ForApplicationDeveloper/html/index.html and Material — Book For Application Developers 10.7 documentation
You may also want to look at the Geant4 basic examples which are included with the distribution.
examples/extended/hadronic/Hadr06/src/DetectorConstruction.cc : lines 98-105
Dear maire,
thank you, I will do this .
Dear mkelsey,
thank you, This helped me a lot .