Three screens, and the middle one is the only one that takes any thought.
Start a new event and give it a name — that name is the title on the invitation and the first thing a guest reads, so call it what you would call it out loud. Backyard cookout. Book club. Mom's 70th.
Pick the day and the time. The quick picks cover tonight, this Saturday and next Friday, and the calendar is there for everything else. An end time is optional; add one if it matters that people know when it finishes.
Say where. Typing a few letters of a place will usually fill in the name and the address together, and My place fills in your own. The address is what draws the map and makes Directions work, so it is worth having, but you can add it later in an update.
Then add the people, and send. Answers start arriving on the event page within minutes.