how can I take from mui wo to hong kong airport using bus..this is my first go to airport.

You can take shuttle bus no.A35 at Mui Wo Ferry Pier, get off at Airport (Passenger Terminal Building) directly. It takes around 65 mins on the way.
In addition, there are only five schedules (05:35, 07:30,17:10,22:00 and 00:15)every day.
The ticket fare is 15 to 25 HKD per person.