Track how many downloads

I'm using google anayltics, but I personally dont care what script I use but I just need to know how many people downloaded my ebook.

I have a picture of my ebook, they click on it, it opens the pdf in their browser, I want to make it where if they click on it, it shows how many people have clicked on it...

Thanks!

That information should be available in the google anayltics for the page that contains the link.
As long as the tracking code has been placed in your html page there should be nothing else to do.

what if its like

ebook.mysite.com which ebook. is a pdf.

How would I track that?

eh?
Just check google anayltics for out bound hits on the link for your page to the pdf.