Not sure what you mean. If you're looking for someone to run shuttle with, you can usually pick up a ride from the takeout back to the put-in by asking around or hitchiking. If you're referring to the act of kayaking as "riding down the river" then it sounds like you are a complete novice and should sign up for lessons and work your way up to a Class III run like Brown's. Even at low water, a novice would unprepared for the challenges posed by Brown's.
Nothing in the world is more yielding and gentle than water. Yet it has no equal for conquering the resistant and tough. The flexible can overcome the unbending; the soft can overcome the hard. - Lao Tse