you will most likely upload it to your "public_html" folder and because I like abstraction, you might want to take advantage of your "new folder" button to create a new folder say, "downloads", and then click "upload (or hover over the icons till you see the tooltip that says same)", navigate to your machine's directory with the file, then upload there.
Then your url would look something like this:
www.sirdayor.com/downloads/ebook.pdfYou might also want to modify your index.html/index.php (or whatever) so that if I type
www.sirdayor.com, I get to see something other than the generic web host home page. You could start with adding text to the effect that you have an ebook ready for download, which could look like so:
<a href="/downloads/ebook.pdf">Download our free ebook today</a>
That should do it. Of course there is more to it than the above and doing any more, sorry, will cost you. Having said that, the little I have done here should get you up and running.
good luck!