Building QGIS - set path to Bison and flex?

I'm trying to follow (probably very good) step by step instructions for building QGIS in a Windows environment hence I've got some difficulties to understand where I shall set the paths for Bison and flex in CMAKE and where do I find the option BINDINGS_GLOBAL_INSTALL?

I've uploaded a print screen from my CMAKE Error message

The C compiler identification is unknown

The CXX compiler identification is unknown

CMake Error at CMakeLists.txt:10 (PROJECT):

No CMAKE_C_COMPILER could be found.

CMake Error at CMakeLists.txt:10 (PROJECT):

No CMAKE_CXX_COMPILER could be found.