In MPI the basic operations are the send
int MPI_Send (void* buf, int count, MPI_Datatype datatype, int dest, int tag, MPI_Comm comm)
int MPI_Recv (void* buf, int count, MPI_Datatype datatype, int source, int tag, MPI_Comm comm, MPI_Status* status)
Next to those, a lot of other different functions exist for non-blocking or all-to-all communication. Programs written with these functions have to be compiled with a specific compiler (options) and executed with a special startup program like detailed here.
Please check the more detailed tutorials in the References.