Congratulations to you and your American Academy graduate!
If you plan to send your student to the DCSD public high school in your feeder area, you do not need to do anything right away. You should receive notification from them in January or February to register for classes. The high schools generally send this information home through the charter schools. Additional information is available on the Middle School page of your current campus.
If you plan to send your student to a private high school, please visit that school's website or contact the school directly for more information about their enrollment process and requirements.