The GPS SD card should have been provided by the seller of the system.
If you didnt get it from him contact him and ask for the SD Card with GPS software + GPS antenna connected to your system. Only then you will be able to use the navigation on your system.
The GPS SD card comes with Navigation system software + maps for Pakistan. Normally the licence is valid for year or in some cases it is open source and you can upgrade the software and maps for free from the internet.