Recently folders labeled with numbers and letters and containing TextEdit.app documents have begun cluttering the hard drive. Why?
How do I create FOLDERS within TextEdit to contain documents created there?
When you are ready to save the document select "Save As..." from the TextEdit File menu. In the Save dialog box that comes up navigate to where you want that folder to be (e.g. your Documents folder) and then click the button near the lower left corner that says "New Folder". Give the folder a name and click the "Create" button.