I picked up a 2005 roadster limited a few weeks ago (nice car, the Crossfire) but don't understand the navigation feature apparently included within my 'Infinity Modulus am/fm stereo single-disc CD audio system' as it is referred to.

Here's what I know: I have the 'Navigation User's Manual' which is intended to tell me all about how to use it, I suppose, but provides no step-one clue that a dummy like me needs to simply get started. The space on the radio face reserved for the navigation feature indicates that 'GPS is OK'. When I press the NAV button on the radion tool bar to boot the system, it directs me to 'insert the Navigation CD'. I don't have the Navigation CD, which is not entirely surprising given the car is pre-owned. Stumped.

What I don't know: How do I go about getting my hands on the Nav CD? Where is the GPS antenna? The user's manual refers to a 'compass' that I should see on the digital radio face somewhere; don't see it. Is this vehicle really equipped with the navigation feature?

I probably don't intend to use the thing - the technology is quite outdated already anyway and I'm not one to truly need a nav system - but it would be nice to be able to play with it. What should I do?

Thanks in advance for your help.