I can see that you gave a decent study on the horse and those statues heads, and did what ever you could do with the form and seeing how the color and lighting works.
If I had to critique, I'll say that keep note and try smoothing out the forms of your artwork and make it more natural since I can obviously see a white out line that makes me distracted on looking at the horse umbrella and the other statue heads plus the rocks in the background. That white outline may work alright if I was looking at the horse (but not the umbrella) and if I was looking at the first main statue head front face (but not the back of its head since I feel that it looks odd).
Even though I may assume this could be the lack of art supplies but not having the proper technique, I feel that even though you depicted a nice difference in lighting and shadows on the horse because of the umbrella, I think the umbrella lack the intensity of the sun hitting on it with that color choice. For the statue heads, things that goes further further back into the background tend to get desaturated a bit and turn closer to blue because of the blue sky.
Overall, work on being confident on your strokes since your form is wobbly, think of the logic behind those photos that you copy and why your picture isn't 99% of the original, and lastly work further on your shading and work with more values with it.