Each school has their own after school program run by a non-profit agency. Some schools may even work with more than one non-profit. Most programs share commonalities such as enrichment activities, homework support, and snacks, and some have additional program specific elements. After school programs in middle and high school also include the official sports teams.
When you apply to schools, there is a box you can check for after-school programs. After you accept an offer to a school, the representatives will contact you about next steps and what you need to do to apply for those programs. This will start in April and continue through the spring and summer.