You seem to have one ATA drive (20 GB) in place already with its jumper set to Master. Just check a couple of things. First, check that the jumper really is set to Master, and not CS. (IF you use CS, you must set BOTH HDD's on an IDE channel to CS.) second, the Master device should be plugged into the END connector on the 80-conductor ribbon cable (usually black).
Then set the new HDD (60 GB) to Slave - as anonymous1 has linked, that means no jumper at all - and connect it to the MIDDLE (probably gray) connector on the same cable.