Played aroud YJs demos - Now where to start

I have been going through the YJs documentation and YJs-demos and wondering where to start. In one of the videos, YJs author mentioned that any online editor could be integrated with YJs. However, really not clear if I need to make too much of changes to the existing editor. As long it is at the backend (no functionality changes to the users) like adding a DB etc. I would like to try it.

I have a custom HTML5 editor (similar to Atlaskit editor) developed in RectJS and the content is saved as files in a folder. We have few nodejs services to work on the content like spell-check, cite references etc.

Just checking if it is possible to integrated YJs here for collaboration. Maxinum 2 to 3 people will be editing at a time.

Add YJs to the simple Textare editor and click of a button show the content as alert is fine with me.

Any pointers where to start.