Speak with school administrators about the possibility of a carnival. You will need the approval of the administration if you want to host a carnival, so prepare a great presentation.
Choose a date. Give yourself at least two months to plan the event, but set a firm date so everyone knows how much time they have.
Put together a team of people who can assist with the carnival. You cannot organize the entire carnival yourself so find some teachers and parents to help and delegate tasks as you see fit.
Work with your committiee to set a time-line for the event. You should have a specific date for contracting food vendors, renting games or rides, bringing in volunteers and talking to the town police and fire departments about presenting safety demonstrations.
Meet at least once per week with your helpers and determine which tasks are falling behind. Constant time-line supervision will prevent a disaster in the last few days before the event.
Put out a call for volunteers about a month before the carnival. You will need parents and teachers to help operate games booths, distribute tickets, control traffic and monitor students.