Firstly, I would like to welcome to you to the art and artist community.

As an artist myself, I sure would tell you that you've made a beautiful attempt here, the act of painting can be scary at times and it happens to even the most successful and professional set of painters, you've started and the more you practice, the better you get. You got get a glue that could hold wood and iron together to repair your broken brush, for the mixing of paint, add white to a particular colour to increase the brightness and intensity for distance, you could mix red, blue, yellow together to get a deep gray which you can then use to tone down the vibrancy of a particular colour to create distance. I hope this helps. Once again, you're welcome here 🤗