how to write the byte code into the processor ?

Answer 1

Are you talking about when the processor is made??? If you are it is done by a series of chemical/mechanical/Implantation of electrons into the silicon wafer.

Or as my mother would say they put the muther F***er on the god d***it.

Answer 2

If you mean a computer processor, then you can't. The closest thing is using the Assambler programming language.
If you mean a dedicated controller or something like that, then you need a special device, generally provided by the chip's manufacturer.