Draw a triangle for the horse's neck, a circle for the cheek and a square for the muzzle. That's all you need for now - we'll add the contours later.
Next draw two straight lines, for the forelegs, two bent ones for the back legs, with balls at the joints as shown. Draw short sloping lines for the horse's fetlocks (ankles) and triangles for the hooves.
If you'd like to learn more about how to look for shapes so you can draw any horse you like, try this lesson on how to draw horses.