I have another question for you!
1. How do I set a sound when loading a custom map?
2. How do I set an image (like a small map) in the game menu (on a custom map)?
3. Please, tell me clearly about the catapult (describe it in more detail), how do I make the catapult shoot at a castle or a fort so that they are destroyed?
PLEASE, HELP!!! KIND PEOPLE!!

1. The LoadingScreenSound property in the map's property tree. There, you either create your own sound and export it (*.mp3, *.wav, or *.ogg), or you can choose from the existing ones.
2. PWLPicture is almost the same. Either create your own and export it (*.tga or *.psd), or choose from the existing ones. Thumbnailimages are the images in the game menu, and pwlpicture is the image when loading. There is a topic about this, although it is not entirely accurate.
3. Create a static object with a catapult model and animation, and below it, create another object without a model, but with an active tile; you can choose the type, for example, AdvMapBuidlingShared. And create the firing animation, city destruction, and triggers for the second object using a script.