First steps with RL78

It is my first time with RL78 and Renesas microcontrollers. I have started a new C project in e2 studio. Microcontroller is R5F10Y47.  CC RL compiler.

I would like to know how to:

- Write option bytes in C source

- Clear the watchdog in the main() function.

Later I would like to do the same with Code Generator, but at this very first moment I would like to learn how to do it in C.