Hi and welcome to DIS. Wishes is the fireworks show at Magic Kingdom and Illuminations is the fireworks show at the World Showcase in Epcot. These shows are usually performed nightly at park closing time. Both of definitely worth arranging your schedule to see. While Illuminations pretty much has to be watched from inside the World Showcase in order to see it good, Wishes can be seen by having dinner at Ca Grill at the Contemporary or Narcooses at GF or by standing on the beach area at Poly. Many people, including myself, book dinner reservations at Ca Grill (or Narcoosees) to coincide with the fireworks for that evening.
For Illuminations, you can either try to book a boat that takes you for a little more private viewing or it's first come to get great locations standing around the World Showcase.
Hope this helps.