mpi.h not found

I tried to compile the Hello World program in C, inside Eclipse PTP, but it gives me an error related to mpi.h. I have included /usr/local/include and /usr/local/lib in my paths, and also tried running a search with find / -name mpi.h. I still get a *No such file or directory* error. I tried to install mpich2, but still couldn't find mpi.h. Also: - There is no folder inside the include directory, why is that? - I can find mpicc at /usr/bin/mpicc The same problem occurs when trying to compile the project as C++ code. What should I do?