You have an incomplete link there. You need some text for the link to appear, something like this:
<center><a href="images/Midwest.pdf"><font color='"#FF0000"'>View PDF</a></font></center>
You don't put width and height on an <a>, just on an image. So if you want people to click on an image rather than a text link, you'd need to create an image of your PDF (you could take a screen shot, for example) and then use code like this:
<img src="images/pdf-pic" width="200" height="200">
So the link point to the pdf, which will open the pdf when they click on it, but what the user sees before hand is an image of the PDF.
You can't just have an empty link like <a href="">. Look at the code for any links on your site. None of them are empty like that. You need a closing </a> tag, with text in between that becomes the linked text. Images are different in this respect.