Copy contents of Old.CSV to a NewExisting.CSV using powershell

Hi All,

Kindly help me in resolving a small powershell code on How to copy contents of an old csv to an existing csv.

Basically i have an old.csv the contents has to be copied to an existing new csv file.

Point of concern:

* New files already exist only contents has to be copied from old csv file to this new one.

Lets say

D:\old.csv,has few data in it and has to copied to D:\New.csv.

Thanks in advance.