High level, you would define a database field in DB that can store text/blob and then pass the entire HTML of your rich text (from your text editor) to play around.
1. NVARCHAR datatype for saving HTML tags in DB
2. Get HTML equivalent of the text editor and save it in DB
3. Retrieve the HTML content when needed and set back the HTML data back into text editor
Following reference would help: Save (Insert) and Retrieve (Display) TinyMCE contents from database in ASP.Net