Need help on the last step to download a csv file to client

I have written the code to create a csv file (actually a tab separated file) stored on a directory on the web server.  The creation is handled on a button_OnClick event.  I understand that I need to set up the Response with mime/type, etc so that the user can download the file to their local computer.  I've googled around, but haven't found the properties I need to set.  Can someone point me to the right place?
 
Thanks

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