Not Find Navigation Software , Please Help?

I have recently purchased a new 7" GPS ( it has not name or brand ) and it is running Microsoft Windows CE 5.0. Now every time i try to press the navigation option i get an error message saying "Not Find Navigation Software. So a few days ago i purchased a brand new SD card and i cant seem to find the maps to put on the sd card. I need to find australian map for the GPS. So what i am asking for is if anyone knows were i can get the australian map , and how to make it work on my gps. Also how do i put it on the SD card. So what i am asking is can someone help get my gps to work i will upload picture of the gps soon that may help , THANK YOU EVERYONE