What do you mean by loading an Adobe PDF file? If u mean uploading than you are to use FTP. You can upload your PDF files just like all the other files.
Or if you mean download than create a link to it in the HTML file. eg:
<a href="pdf.pdf">click here</a>
If you ment uploading via your website, than you might want to google for solution: file uploader php
Prolly the first 5 results will give you the answer.