How can I proceed to Yancheng from Pudong airport & what are the timing for bus, & how long it takes

There is no direct bus between the two places. You can take the airport shuttle line 7 to the South Railway Station. Then walk to the South Bus Station to take bus to Yancheng. They run every 30 minutes from 06:50 to 21:30. It takes about 4 hours and costs CNY20.