Online campaigns have different categories, depending on the target market you are trying to reach and the duration you would want to run. You can advertise in different categories such as banner ads and email marketing.
Identifying Your Target Market
Have you identified where in the US you would want to market your school? There are plenty of options, with Google Ads and Facebook Ads being some of them. Please focus on the demographics and region you would want to reach, and then finalize the budget that you may consider spending. You may even consider specific communities if you are targeting a niche.
Looking forward to hearing from you.
Regards