Although you have no work experience, there are tons of skills that can be applied to the workforce that you have learned while being in school.
Therefore I would start with making a resume:
1: List an objective at the top: For example, “To obtain a part-time position, with opportunities for training and advancement where I can use my skills and gain further work experience.”
1: List skills that you may have such as determined, motivated, punctual etc.,
2: If you ever volunteered or participated an, any extra curricular activities list those as well.
3: List your education (high school graduate)
Once you’ve created a resume start with applying to entry level jobs so you can begin to gain that work experience. Online is usually the best method to apply for most companies and find openings.