I need to add a lib like /usr/local/lib/libYARP_OS.so in my program and an include like
/usr/local/include/yarp/.

I setup the following environnement variables in the qtcreator->project->build environement
INCLUDE_PATH=/usr/local/lib/libYARP_OS.so
LD_LIBRARY_PATH=/usr/local/include/yarp/

But when I compile it is still doesnt find yarp... Do you have any idea ?