I download 'httrack-3.46.1.tar.gz' with source code and want to add my custom
callback plugin.

Where is the place to save my custom file and compile it?
I was saved my file to 'src' folder and compile:

[root@THMT0008 src]# gcc -O -g3 -shared -o mylibrary.so myexample.c
In file included from httrack-library.h:41,
                 from myexample.c:7:
htsglobal.h:132:20: error: config.h: No such file or directory
myexample.c: In function ‘hts_unplug’:
myexample.c:67: error: ‘stder’ undeclared (first use in this function)
myexample.c:67: error: (Each undeclared identifier is reported only once
myexample.c:67: error: for each function it appears in.)
 
please help.

sorry for my poor english.