hi, how do i go from shanghai to Tanghou. see Mount Huanshan and go further to Hangzhou?

I think you may mean Tangkou, right?
If so, you can take a bus from Shanghai South Bus Station to reach Tunxi Bus Station where you can find the direct buses for Tangkou.
To be honest, from the south bus station, you can find the direct bus to reach Huangshan attraction directly.
From Huangshan Attraction Bus Station, there are direct buses to reach Hangzhou directly and the buses are at 06:40, 06:50, 07:40, 14:15, 15:30, 16:30 and 17:10.