CodeMirror 6 is hard to integrate

When I am trying to integrate the verion6 into my code, it’s hard to integrate for me. The document I cannot understand well. No sample code available for reference.
I spent about afternoon trying to understand the doc CodeMirror System Guide, State and Updates make me confused. I still don’t know how to replace all text to another piece of text.(the document shows update({changes: {from: 0, insert: ''}))

For example:
I take an hour to integrate the below code:

  let editorState = EditorState.create({
	doc: "",

  let editorView = new EditorView({
	state: editorState,
	parent: editorContainer,

But I don’t know how to finish the next steps. For example, If I want to enable line number, the document gives me these:

### Gutters
Functionality for showing "gutters" (for line numbers or other purposes) on the side of the editor. See also the [gutter example](

`lineNumbers(config⁠?: Object = {}) → Extension`
Create a line number gutter extension..........

I don’t know how to use the gutter. it doesn’t show the belong module and no example code.