Save/Read .csv text file from Clients Machine

I need a small project done for me that allows the user to save text that I generate to a csv file ... I cannot save the data to my system as it will be confidential information it must be saved to the uses own computer .. but I want to have the ability that the next time they come they can browse to the .csv file created by our system ... my program reads the data from the .csv file to utilize however I see fit ... Again the user needs to save the output of some text I generate to a csv file to there system with a browse button or something and then when they come back to the site they can upload it again ... xml would be fine too ... I am using sql server and asp.net to develop with. Preferrable this will be done completely with code ... it would be nice if you setup and example before I paid .. but once i saw the example and it worked the way i wanted to i can pay or upon me testing it and being happy with it on my own server then I can pay the as well.