Choose Settings from the Format menu.
The default left margin is 0 and the right margin is dynamically set to the width of the Text Editor window. Margins are specified as a number of character columns.
Determine the scope of the formatting:
To format a single paragraph, place the cursor in the paragraph, then click Paragraph.
To format the entire document, click All.
After closing the dialog box, choose Paragraph or All from the Format menu to apply the settings.