downloading files from a url.

Hi! I am new at php so i dont know how to use it. I would like to download pdf from a certain url.Found the code to for this issue. But it downloads the file immediately with now info message.So i decided to have a popup window which asks me if i want to download it or not. So i use the headers.But it creates the pdf with 0KB (basically it doesnt get downloaded). What method should i use to know if i pressed yes or discard for the download process in the window dialog? Do you have any sample code to help me out with this? Thanks in advance, Caroline