i will be landing hong kong international airport at 6.50 am want to go to guangzhou via ferry.

You can take a ferry to Lianhuagang Port from HKIA. The first ferry departs at 11:20. You need to pay HKD 300 for an ordinary class; HKD 350 for a first class; HKD 400 for a VIP class.

Or, you can take a bus to Guangzhou from Coach Station, T2, HKIA. The first bus departs at 7:00. The fare is HKD 250, and trip takes 3.5 to 4 hours. :)