Start by drawing two overlapping circles for your horse's head.

Below that draw a larger circle for the shoulders and another for its hindquarters

Next, draw some joining line on the head to create a muzzle.

Make the neck by joining the head to the shoulders.
Then draw some joining lines between the shoulders and the hindquarters to make the body.

Onto the legs.
Horse legs can be a bit tricky so try copying the bumps and curves on the picture. Include some ovals at the bottom for hooves.

Draw two triangles for the ears make the closest one the bigger.
Then draw on the tail. You can make it as long and wavy as you like.

Clean off some of the lines you don't need.

Add a couple of circles for the eye and nose. And let's not forget to add in the mane.

You might like to square off the bottom of your horse's hooves

Add some colour to your horse and it is finished.
This one is a chestnut with white blaze and muzzle.