Wishes is the fireworks show at the Magic Kingdom.
You can see it from almost anywhere in the park or from one of the three monorail resorts. Some good places to catch it are from the bridge going into Tomorrow Land, from Main Street, or if you have little ones you can see most of it from Pooh's new kiddie park(sorry I forget the exact title of that area at the moment). At one point Tinkerbell comes out of the Castle and flies over the crowd. I do not know if she can be seen from anywhere other than the bridge or Main street.
Have a great time.