Try reading this manual for Blaupunkt blaupunkt philadelphia 835
[Please Register or Login to download file] it might not be the same model but there should not be too many differences.
there is a cover on the right hand side which when open has a micro SD card slot behind it.
is there a micro SD card in it ?
if yes test it in a PC to see what software it has on it,
if no you need to get one and install iGoPrimo on it.
when you press the navigation icon it loads the navigation software from that micro SD card.