Talk to Storn | Main story mode - The Fate of the Skaal TES V: Skyrim - Dragonborn Guide
Last update: 11 May 2016
Return to the Skaal Village and search for Storn Crag-Strider (he's most likely in his house - the Shaman's Hut). Speak to him to end the current mission and begin two more - Cleansing the Stones and The Path of Knowledge. The order in which you complete them doesn't matter you will have to finish both of them eventually.