http://curl.haxx.se/libcurl/c/libcurl-tutorial.html
Linking the Program with libcurl
When having compiled the program, you need to link your object files to create a single executable. For that to succeed, you need to link with libcurl and possibly also with other libraries that libcurl itself depends on. Like the OpenSSL libraries, but even some standard OS libraries may be needed on the command line. To figure out which flags to use, once again the 'curl-config' tool comes to the rescue:
$ curl-config --libs
si y t'ennuie à cause des libs ssl, enlève -lssl et -lcrypto, t'en as pas besoin de toute façon