Knytt Stories + (plus)

I have downloaded KS+ and The World is Changing by toenail for KS+. I saw that he made gold objects (the first one is a flyer) which you can collect to open doors in a similar way to having keys and opening the door/lock of the same color. They also appear in your power-up bar.
I also saw that he changed Juni into a ghost which you can move around just like Juni.
Can anyone tell me how to do this?

First make sure you've downloaded both the KS+ player and the KS+ level editor. With them will come two text documents - one called 'KS+ instructions' and the other called 'KS+ readme'; they should tell you how most of the KS+ features work. Also, you may want to download and play egomassive's level 'Features Demonstration' for a more complete array of the mod's possibilities.

You can find a selection of custom character spritesheets made by other players in this thread if you want to see what's already available.

Thanks!