i cant figure out how to place a mark(like a green dot) on the place where you click with your mouse. so how can i make a mark of where the player has clicked and gets removed when the player is at the location or has clicked on a another spot.
Simple, use raycastHit and set the players move destination to the hit.point (and convert to transform).
And to remove the green dot you can use Vector3.Distance to get the distance between the player and the green dot. When its low enough remove the dot.