Ask your drama department in your school. Chances are you'll be able to find some to help you. Try for year 11 students, as HSC students are just as busy as you are.
Local theatre groups are a great way of finding actors. Most area have some form of youth theatre group where you can find actors.
Ask your friends, particuarly if their good performers, or even good at speeches.
Dance academies as well may have actors. A lot do both acting/dancing.
Professional actors is going to be harder, and it costs a lot. I wouldn't recommend this.