there is am info how to update navigation maps for your system. It's on official website:
[Only registered and activated users can see links. ]
(check on the right side - "Maps update procedure")
But anyway I believe that you wanna try with the "cheaper" version right?
I personally don't have any experience with this brand, but I'm afraid that that this is one of many similar systems with iGO Primo navigation software on the internal memory/flash (only maps on a SD) and that is really hard nut to crack. First of all post here some screens of your SD card (if you have it) and than we can see the basic file/folder structure of the navigation SW.