Markdown content created with SimpleMDE
I would like to be able to collaborate. . .
I do not know what work is required. .

Currently, markdown is implemented with the following code

var simplemde = new SimpleMDE ({
  element: document.getElementById ("editor"),
  toolbar: ["heading-1", "heading-smaller", "heading-bigger", "|", "bold", "italic", "strikethrough", "code", "|", "unordered-list" , "ordered-list", "link", "table", "image", "|", "preview", "guide"]

It is a beginner and understands almost only on a copy and paste basis. .
I visited various sites and tried, but I couldn't solve it ...

Error message

I'm in trouble
① I don't know how to store markdowns
② I don't know how to collaborate in real time

If i know how to store the data in (1)
② store data in firebase's real-time database
If i can bring that value, you can go. . . I have a delusion.
I don't know how to implement orz