But there's something I'm still confused about. I don't know how to use the map editor. I want to create my own map so badly. I know the basic controls like moving and placing blocks, but I don't know how to paint, etc.
True, a lot of things are not very self-explanatory, sorry about that!
I am working on an interactive tutorial for the next version which should become available soon. Until then, please check out this video tutorial (understandably, it's less interesting when it's a video):
Thank you for taking the time to make maps!