Upload the file to your Media Library and link to it using HTML anywhere in your theme.
<a href="http://www.example.dev/wp-content/uploads/2014/01/logo.jpg">Download this image</a>
Upload the file to your Media Library and link to it using HTML anywhere in your theme.
<a href="http://www.example.dev/wp-content/uploads/2014/01/logo.jpg">Download this image</a>