Find the swinging bridge landmark in Byram, MS. That will be the starting point. The ending destination is Rosemary Bridge off of Rosemary Rd in Terry, MS. It's the second single-lane bridge on the road if you are coming from the terry way.
Anyways - there were VERY few rapids or quick water along the trip. It's very relaxing and slow most of the way which is great for fishing. There are several areas to find crustaceous period fossils and we counted 36 waterfalls along the way. The trip is about 11.2 miles total and will take most of the day.
CAUTION: there will be wildlife along the way, aka alligators. You respect them and they will leave you alone as well. Have fun and hope this helps.