There are various videos on the internet documenting the use of the built-in level editor. This is a list of some of the useful ones. However, due to the nature of the internet this list is probably incomplete. You're always welcome to add new ones!
- Basic Tutorial by brmbrmcar
- Basic Tutorial (Part 1/2) by Oliver Buo
- Basic Tutorial (Part 2/2) by Oliver Buo
- Advanced Tutorial (Part 1/2) by Oliver Buo
- Advanced Tutorial (Part 2/2) by Oliver Buo
- Expert Tutorial by Oliver Buo