Barn Bluff is a great place for a family hike. You can even bring the dog along as long as it's on a leash. The south trail is the best route. After parking your car take the steps to the information kiosk. You will see a map and a description of the trails and a lot of history about this landmark and the role it played in the history of Red Wing. I strongly discourage you from taking the North Trail. In recent years several hikers were injured on that trail, including one fatallity. The city plans to fix that trail, but until they do do not use it.
On a recent fall day my wife and I met many families enjoying the South Trail, which is the best route to the cache. The cache is located within a few feet of the Kiwanis Stairway, which was re-built in 1982. 114 steps will take you up the steep area that would be a dangerous strech if it wasn't for the stairway. The veiw is great at the top. After looking to the west and the city of Red Wing take the Prairie Trail to the east end where you will be able to see miles downriver. All of the trails are well marked.
You are looking for a small container. You probably do not need the hint as this is an easy find.