How to make a Send to Kindle button

Hi,

I want to add a send to kindle button on my website where I am giving away a free Kindle mobi file. How do I make the .mobi hyperlink on the page into a Send to kindle button so it will send the eBook directly to my readers Kindle account? I have seen other websites with this feature and think it would be great for my readers. All I can get to work is sending the whole web page to Kindle, not the mobi file in the hyperlink.

Thanks for any help!
Karen