After investigating the Earth Stone Shrine
and speaking to Neloth, you now need to trek to the Temple of Miraak. The Temple of Miraak is located to the Northeast of the Earth Stone Shrine (and of Raven Rock), see the map below for a possible path you could take:
When you arrive at the temple, go down the stairs to the center of what appears to be some sort of shrine or theatre. Look for a white arrow which will point you to the exact spot you need to go to. Once you reach that spot, the quest "Dragonborn" will complete, and the next quest "The Temple of Miraak", starts.
Your first objective is to talk to Frea. Frea is should be standing near by. Approach her. When she see you, see calls out to you:
"You there. What brings you to this place? Why are you here?"
Ask her who she is. She tells you that she is Frea of the Skaal. She is here to either save her people, or avenge them. Ask her what she wants to save them from. She says that she is unsure. Something has take control of most of the people of Solstheim. It makes them forget themselves, and work on horrible creations that corrupt the stones, the very land itself. Her father, Storn, their shaman, says Miraak has returned to Solstheim, but that is impossible.
Tell Frea that the Miraak tried to have you killed. She says that you and her both have reason to see what lies beneath you. Se suggests that you and her go, there is nothing more she can do here. The Tree Stone and her friends are beyond her help for now. You need to find a way into the temple below.
This completes the objective "Talk to Frea" and gives you your next objective, to find the source of Miraak's Power.