Download a data in several format according to our choice.

Question

Hi all,
I have a dropdownlist,one multiline textbox, RadioButtonList and a button.when page is loaded names are attached to dropdownlist and when i choose and name from the dropdownlist corresponding details are shown in the textbox.
Now i want to download it with several format like .doc,.pdf,.txt .To do it in RadioButtonList there are three ListItems (doc,pdf,txt).when i choose one of those ListItem and click download button,it will download according to the format i have selected in listitem.
 
Thanks