How would I improve music lessons at my school (as a student in year 9)?

Here is an organization that helps in California schools. Do a search in your state for similar programs. You will probably need a lobby effort to get support from your local school board. You may have to start a music club and use it as an after school activity. Contact any music organizations in your area for help. A lot of areas have instrument drives to get musical instruments out of people's attics and into the hands of kids. Your initial goal is to not cost the school any money. Music programs are usually the first programs to face the budget axe. Best wishes.