It is a separately ticketed event. So you buy a party ticket and you are able to enter MK at 4pm. You do not need a park reservation or a regular day park ticket. The party includes most rides (but not all) and most shopping (but not all) as well as special extras such as special shopping, food items, shows, and attraction overlays. In addition, adults can wear costumes (within guidelines). Dates are announced sometime between Feb and April (based on previous years) and often sell out by August. The parties run from (generally) the second Friday in August until Halloween. What else are you wondering about? I'm always happy to talk Halloween....