Cleaning Print Heads on HP Deskjet 5550

Hi,

I am trying to find out how to clean the print heads and perform other
general maintenance operations on my printer. I have tried Printing
Preferences and Properties as well as the trouble shooter but cannot
find the page I am looking for. I did it once by accident but cannot
remember how I managed it!!
At the moment I am unable to use my colour printer because the black
ink will not print as I recently changed the cartridge.

Many thnaks,
Dee