TomS_ can i give me an example cord ? thank you !
Well, the idea was to give you some information which you could then use to discover the answer yourself so that you can learn.
If you know that value X needs to be stored in 16 bits, and you need to be able to store that value into an EEPROM which only handles 8 bits at a time, and assuming there is no existing way to do this, then you need to discover how to split a 16 bit value into two 8 bit values.
I'll give you some hints: one of them is using logical shifts. The other could be pointers and casting (but I would start with shifts).