For the Walking Dips, position yourself on the parallel bars as if you are going to do a normal dip. Lower yourself down and as you explode up, move one arm forward. To continue the exercise, repeat the same motion, but with the opposite arm. Continue this motion to simulate walking across the entire parallel bars. To make the exercise easier, decrease the amount of dip between "steps", or don't dip at all.
This exercise mainly focuses on the triceps and chest. The walking motion places your body in a skewed position which puts more muscular strain on one side of the body. This position also requires a forward lean that favors more use of the chest muscles.