You can also see your guidance counselor about going back or about continuation school, adult education classes, or a high school equivalency diploma. A continuation school is for students who have dropped out of school to go to work. The classes meet after work. Adult education classes usually do not give high school credit, but they do offer practical courses that can help you earn a living. You may be able to get a high school equivalency diploma without going to school.
Some people get enough from books to pass the test.
Other people can do it with the help of friends, neighbors, or teachers. If you are still in school, supporting yourself probably won't be possible, but you should be able to contribute to expenses. Before looking for any kind of a job, see your school guidance counselor to find out how child labor laws and the laws about compulsory education affect you. There are many ways of finding a job besides the help wanted ads. Ask friends and relatives if there is a job where they work or if they know of a place that needs someone with your skills.