You can drag documents around in the Binder area at will.
This sounds confused in a way that probably needs straightening out. The first procedure you describe sounds perfectly fine — typing text into document items and grouping text documents under folders is a very normal way to operate. So, I am concerned about the lesson you think you have learned and the new procedure. In particular, in the new way you say you create a folder “and then start [your] copy instead of adding a text doc under it.” The million dollar question is: into what place is your copy getting typed if not into a text document?? The text must be going into some file or other which is represented in the Binder. I very much suspect you may now be typing your copy into the text body area of the folder itself. This is a little like typing your text directly onto a manila folder instead of onto the sheets of paper in the folder. While it is possible to work this way, it probably not what you mean to be doing, and for a beginner often leads later to confusion.
If later down the road it suddenly seems distressingly like all your copy text has vanished (except in Scrivenings view) this will be why: you typed your text onto the folder itself (and have changed the apps view to one where folders don’t display their own text contents, but instead show you the files under them — as a corkboard or an outline or whatever).
To get a clearer picture of where your text lives toggle off Scrivenings view so when you click on a Binder item it gives you Single Item view and so just shows you what text is entered into that particular Binder item.
By the way, if you do find you typed text directly onto the folder itself and want to change that, you can just convert that folder to a text file. Control-click on the folder and choose Convert to Text Doc.