gforth: fflib.fs and calling c libraries ( was prev: libffg2: gforth

I found this helpful link with loads of examples:

http://www.shockfamily.net/cedric/fflib.html

With my current gforth: 0.6.2 - which I remade after make-installing
ffcall. I still get the following error message:

____________________________________
s" fflib.fs" REQUIRED
in file included from *the terminal*:2
/usr/share/gforth/0.6.2/fflib.fs:121: Undefined word
' av-int      ' av-int-r      ' >r  argtype int
  ^^^^^^
Backtrace:
$B7A39CBC throw
$B7A39CE0 (')
____________________________________

So... no libc6 or Xlib or GTK yet :(

I am just wondering if I am missing out on something very vital in the
entire make process of either gforth or ffcall.

How exactly did you guys put in ffcall into your gforths?