I have to download following
<a href="">Please Download Sample file</a>
Use the href to link to the document that you want the user to download. So you need to have the url to what should be downloaded, or point to it on your server. Adding download to the html markup will have it download, better to leave it to the user to decide though...
<a href="http://www.pdf995.com/samples/pdf.pdf" download>Click to download</a>