how to apply visa for hongkong? what are the requirements?

hi.we are planning with my husband to visit disneyland(hongkong) and macau if Gods willing by next year 2012 i will bring with me my parents(they are senior cetizen)and both retired from work and my 5 years old son for sight seeing and leisure time only (just a gift for them) for them to be happy ,would they need to provide the requirements for the first timer to visit HK too,its my first time too. could you please send me an info of what to do and the requirements.thanks.