How much money can I expect to make in fast food...?

You won't make much. They won't usually hire anyone under 16. You can expect minimum wage, and if your in high school probably not over 30 hours a week. So... 30 hours a week times 7.50 an hour is 225 dollars a week, times 4 weeks in a month is 900 a month, times 12 months a year is 10,800 a year.... Basically, you'll set yourself up for a dead end job. Try to find something more interesting or related to what you would like to do with your life and you will set yourself up for success later down the road.