-ed tells us the effect that something has on someone. It is used to tell us how someone feels.
        I am excited. (how I feel)
-ing tells us something about the subject; it describes it (not how it feels).
        This movie is exciting. (about the movie)

Other examples:
I am tired. The meeting was tiring.
I am amazed by her work. Her work is amazing.
I am surprised! That announcement was surprising.
confused/confusing
worried/worrying
annoyed/annoying