By default, text is aligned with the left edge of the page. You can center text or align it with the right edge instead:
Optionally, you can click the alignment buttons in the Paragraph Composition palette of the Palettes menu.
To change the justification of multiple paragraphs, click the left mouse button and drag across the paragraphs that you wish to modify, and then follow the above procedure.
To change the justification of the entire document, choose Edit > Select All, then follow the above procedure.