If you start a new town, the place where the festivals happen is already set to change. So don't do anything. If you start an old save, it should come up with a thing asking you if you want to place the festival lot in your town.
If neither of the above is happening, it's possible that the lot is somehow missing the " seasonal lot marker." To place one, first go to the lot and open up the cheat box by pressing ctrl, shift and c. Then type into the box - testingcheatsenabled true. Then open up the box again and this time type in: buydebug on. Go to the sort by function section in buy mode. You should see a square with a question mark, go into it. Go to the misc. objects and scroll down until you see a round black circle, there will be quite a few so keep on scrolling down until you find the one called "seasonal lot marker". Place it on the lot.
To get rid of the cheats, open the cheat box and type in: buydebug off. Then open it again and type in: testingcheatsenabled false. It MUST be in this order, if you do it vice-versa you can't turn off buydebug and it just gets really complicated.
Let us know what happens and I hope this helps! Welcome to the Answer HQ!
