To access the Plan a Game feature for an upcoming event, tap Events tab at the bottom, then tap into the event or convention you want to create a game at. Tapping Plan a Game from inside the event means your game will be set up to happen at that event/convention.
Planning a Game in a convention works the same way as planning a game normally, with slightly different location options. Rather than an address (the address is the convention location), you can enter instructions on how other players can find you. This could be an identifying article of clothing, a table number, or anything else that will help you pick each other out of the crowd.
You can always chat with your group to keep them updated and edit the event details if things change on the day.
Your game will show up in the list of games happening at the event.
The list of event games is found in the Full schedule (above) on your event page.
The schedule (shown right) is presented chronologically and can be filtered and sorted for easy browsing.