How to make text behave as a hyperlink in PDF exported from Adobe InDesign 5.5

There are two things required for creating functional hyperlinks in a PDF from InDesign:

1. Link defined in Hyperlinks panel
2. PDF Export supporting hyperlinks.

If you've already created the definition in the Hyperlinks panel as @Scott recommended, then my bet is that you are using an PDF export that doesn't support interactivity, and those hyperlink settings are being ignored when generating the PDF.

I don't have version 5.5, so I can't verify exactly what your screens look like, but in CC, there are two ways to include interactive elements - it should be similar for you:

Option 1

Select Adobe PDF (Interactive) when choosing the filename:

Then set whatever options you like on the Export Settings dialogue.

Option 2

If you select Adobe PDF (Print), or if you only have one PDF export option when choosing the filename, then in the PDF options dialogue, be sure to make sure Hyperlinks is checked in the Interactive section.