Ambient dose equivalent H*(10)

Hi, for my dissertation thesis I must calculate H*(10) in MCNP or Geant4.
How can I do it exactly? What does 10 mm represents? What tally do I need to use at 10 mm in MCNP? Then, this tally will be multiplied by H*(10,E)/F, and from where can I get these H*(10,E)/F values?

Please, it’s really urgent.