DD4hep stands for Detector Description for HEP, a software package developed in the context of AIDA WP2. DD4hep is based on the ROOT geometry framework TGeo and thus allows to use all its features. DD4hep provides representations of all TGeo shapes and means to place them in a hierarchy of detector elements with additional information, which is the core feature of DD4hep.
The manual, presentations, and information of how to check out the source code can be found at
Getting the software to run and follow some of the simple examples should be straight forward and should be possible within days. The steps to follow are listed in this readme.