On the folder "PlugInDoc" provided within installation.
There is PDF with documentations, and (some are outdated but still usable) samples for Delphi and C++
Note: if you want to use Visual Studio, 64 bits plugin created won't load into version 11. 64 bits created from Delphi on C++ Builder work fine. It is fixed in the upcoming Version 12 (See the Beta area of the forum)