How do I insert internal links to other pages within a PDF document?

How do I insert internal links to other pages within a PDF document? e.g., link pages to a table of contents? I have a document scanned to PDF and using Adobe XI Pro. The document contains a Table of Contents. I would like to create links from the section/chapter titles on the TOC to the corresponding pages found later in the document. Not sure this is even possible, but please advise if there is a way this can be done. Thanks

Brian Bee