You would read in the csv, edit what you need or add/remove data, then write a new file or overwrite the old one. You don't need to implement any interface, there are tools that do all of this. You could probably write the code up for something simple like this in the time it takes for excel to open the file and you to make the change manually by finding the field, clicking away with the mouse, and typing it into the cell. Specifics beyond that can be searched for on the internet as there are a wide variety of methods you could tailor to your purpose.