excel how to update from one xlm file to another

i have a line which says the line number say:
z1
z2
z3
z4
and so on..
i want to make a program which takes an xlm file and update another xlm file by here line
lets say the line was
z1 name3
z2 name4
z3 name2
after the update it will be what it was in the updated xlm file