To add a link to a PDF document:

Choose what you want the user to click by doing one of the following
If you want the user to click some text, select the text and choose Tools > Annotate > Add Link.
If you want the user to click a picture, choose Tools > Annotate > Add Link, and then drag the cursor over the picture.

Choose the link’s destination by doing one of the following:
If you want to link to a website, choose URL from the Action pop-up menu, and enter the full website address in the URL field.
If you want to link to another page in your PDF document, choose “Link within PDF” from the Action pop-up menu, go to the page you want to link to, and then click Set Destination.