Salam Mohd
If you use C language define array of unsigned integer which is 16 bit (compiler dependant) where you can place it in code memory or data memory.
If you use assembly language and you have 8 bit microcontroller you split the 16 bit into 2 bytes and store them as 2 byte values at DPTR, DPTR+1. then you have to increment DPTR by 2 to access the second 16 bit value and so on.
up to you how to store the order of the bytes but you have to stick to the convention you make otherwise you will corrupt your 16 bit value.
Mahmood