Once you reach the Hinterlands zone, travel to the far western corner to investigate the "Master Of Horses" side-quest. It is west of the Redcliffe Farms Camp. You can see the large stables from a distance. Travel up the hill to the large homestead, talk to Master Dennet, and agree to his terms to get a free Ferelden Forder. You can collect the horse with the saddles in the stables to the right of the path as you exit the house.