It appears by your question that you have dropped out of high school and now want to get a diploma. You should make an appointment with your local high school's guidance counselor to talk about your situation. Based on that meeting a plan of action for you can be developed. For example, your best option may be to get a GED, which is equivalent to a high school diploma.
My main recommendation- talk with someone at your local high school for suggestions about next steps.
You can go to adult education and get a diploma through adult education.That is what I did.Just go to the high school you used to go to and find out where there is adult education in your area and get the information you need to start.It is much easier than regular high school and much more enjoyable.