Hi, iam from Vietnam. I will go to HK on 30 may to 4 jun 2013 with 2 chidren

You can take the airpor express to reach Kowloon Station and then take the free shuttle bus K5 to reach your hotel.
For the places to go, I suggest you arrange your route like this:
Day one: Ngong Ping 360, Tung Chung Town, Big Buddha and the Disneyland.
Day two: Ocean Park, the Peak, Victoria Bay and the Star of Avenue
Day three: Stanley Market, Causeway Bay and the Symphony of Lights.
Then I suggested to go a trip in Macau where you can go to see the Ruins of St. Paul's, Venetian, the Grand Lisboa, A-Ma Temple, Macau Tower and the Avenida de Almeida Ribeiro area.
Besides, you can refer to https://www.travelchinaguide.com/attraction/hongkong/ to find some more interesting place that you want to go to have a look.