which bus to take from hongkong airport to harbour city Tsim Sha Tsui, how much is the fare?

There is no direct bus to take you there.
You can take airport shuttle S1 to reach Tung Chung. Then change to Tung Chung Line to reach Lai King where you can change to Tsuen Wan Line to reach Tsim Sha Tsui. Getting out of the station from Exit A1, you can see the harbour city.
It may cost you about 18.5HK$ in total.