Pages 190-192 of the AMA Competition Regulations contain the rules for Competition FUN-FLY, AMA rule-book event 705.

There are many many ideas. There are timed tasks, Limbo tasks, Mission tasks and with a little imagination, mix & match, and stirring the pot, one can devise a FUN-FLY of choice from easy stuff to serious hard-core competition, just whatever one might want.

While there is nothing there mandatory, there are numerous ideas and guidelines.
Throw in your own seasoning and have a blast.

Now some advice for a new CD; I know you did NOT ask that however here is a way to start a good day.
1. Before the day, have all your paperwork filled out as much as possible and someone to handle registration. Be sure to have plenty score sheets clipboards, pencil-pens, etc.
Be certain you have adequate judges that will SHOW!
2. Frequency control/transmitter impound is a near must. Don't be shy with the slow-to-impound which there are always a few.
3. Have a serious Pilot Briefing to include all your safety rules. At my meets, 3 strikes are for baseball only so it is TWO strikes and its outsville. (I have not had to dismiss a pilot in over 10 years of doing 3 to 5 events per year. I have had to call Strike One at many events. We all forget now and then) Simply be firm and fair and the guys will always help you out. Give those prima donnas an inch and they want a mile. Don't give that inch and they do fine. DO NOT be intimidated by anyone.
4. I never change an advertised rule UNLESS 100% want that change during the Pilot Briefing. Changing an advertised rule because someone else did it differently before unfairly discriminates against those that came to play by the advertised rules. Any change later would only happen if there was some serious safety hazard which prior planning precludes such an item.
At AMA Sanctioned events the CD is the Captain of the Ship. OTOH, as ship's captain you CAN delegate authority, but you cannot delegate responsibility.
Just be prepared and a new CD will have more fun than the visitors, and be MUCH MORE tired at day's end.