Check with the Financial Aid office of the school(s) he is considering. They will guide you.
Also check with civic organizations (like Kiwanis or the NAACP), professional organizations (like the FFA or the National Society of Accountants), charitable foundations (like the Gates Foundation), subject-oriented organizations (like the National Science Foundation), cultural organizations (like the German-American Society), service organizations (like the DAR), and churches... and more.
Applying for serious financial aid is a serious, time-consuming job. It is WORK. No matter what some people will tell you, there is no one application that covers everything. You must be very organized, and be sure to meet all deadlines and application requirements, and to keep track of the names and dates of everyone to whom you speak.
Often, the FAFSA and ACT/SAT score will trigger scholarship offers administered by the school... but for the others, you may have to apply individually to each organization.