D drive empty - all saves to C drive. Inspiron 1564 / Windows 7

I've seen several threads asking this question but none seem to have received a satisfactory reply that I can find.

My system (Inspiron 1564 - Windows 7) is still configured as I received it from Dell. The C drive is 58.5 Gb and the D drive is 164 Gb.

The problem is that everything saves to the C drive and nothing uses the D drive.

I do not want to reformat in one drive, happy to keep 2 but want pictures, documents etc to be saved to the D drive as the C drive is getting full up. How do I make the change to point these files to the D drive?????