Hi khelifac,
Are you wanting to add a link to a PDF file, or create a link to a PDF file, so that you can share that PDF with others?
If you want to add a link to a PDF, then you'll want to use Acrobat. You can download a free 30-day trial of Acrobat from http://www.adobe.com/products/acrobat.html.
If you want to create a link to a PDF file so that you can share that file, you can use Adobe Send. Log on to https://cloud.acrobat.com with your Adobe ID and password, and then click Send. Click Select Files to Send, and then navigate to the PDF file. Select Create Anonymous Link, and then click Create Link.
Best,
Sara