a - read the manual and exercise the lens a bit (http://rawhiti.tripod.com/retina2typ...ionmanual.html)
b - take some pictures of your grandparents with it, the pictures will have special value and they may be pleasantly surprised with the quality of that camera

They'll love you for it (well, love you even more for it).

I still use my Retina II and Retina III.