What should we exact do in third quest?
upgrade your townhall the main building to lv 3
It says "town hall", but I think it means "main hall" because there is no town hall. Click on it, then click the upgrade tab, then upgrade it all the way to 3. It will take hours. Not sure how many in total, but it takes about 3.5 hours to go from 2 to 3... so make sure you have plenty of time left to complete the quest. :)