I read the official manual of VR tutorial, but unfortunately there isn’t a C++ tutorial about it, just python only.
What should I do? Or maybe I can try to figure it out and help complete the doc manual…?
Are you referring to this page (http://www.panda3d.org/manual/index.php/VR_Helmets_and_Trackers)? If so, that is specifically for CMU’s setup, and not for modern VR HMDs like the Vive or Oculus Rift. Panda3D does not, currently, have support for modern VR headsets, but I think there was some experimental stuff at some point.
If you actually have and want to use the CMU hardware, then I suspect that VRHandler module may be for Python only.