Hi!
Essentially the way you make a hyperlink in Decker is selecting the text you want to be the link, and then using the Text -> Link... menu option, which then gives you a dialogue box that you can fill in either a URL or the name of a card that you want the link to go to. In order for the link to be clickable you will need to lock the text box from interaction.
No scripting required unless you want the link to do something more complicated than going to another card or URL - that's the situation where you'd want to override the default behaviour.
Hope this makes sense.