I have done so:
C:\>where pkg-config
the output was:
C:\freesw\bin\pkg-config.exe
so I tried something else I downloaded the 32-bit version and ran it, it worked although I have 64-bit windows (I checked it), now there is a new error:
-- No package 'glib-2.0' found
-- No package 'gthread-2.0' found
both of them are in the folder as in the wiki:
C:\freesw\
├───bin
├───include
│ └───glib-2.0
│ ├───gio
│ ├───glib
│ └───gobject
├───lib
│ └───glib-2.0
│ └───include
├───manifest
├───pkgconfig
├───share
│ ├───aclocal
thanks for the help