getting Kdevelop to look for includes

Hi all, I'm new to programming in Linux and have picked up Kdevelop in the last few days. I'm currently building my first project with C++ and am playing with SDL. However, when I try and compile, i'm being told that SDL.h cannot be found. The compiler only appears to be looking in /usr/include/g++ and my SDL libraries are in /usr/include/SDL How can I open up its search path? Thanks in advance.