Your content is automatically set to be "published," which means it is visible to the public. To change your publishing options from automatically being public, click the edit button of the page you want to un-publish.
While in the edit mode, scroll toward the bottom of the page until you see Publishing options. Uncheck the “Published” box. Then click Save.
If you know HTML, use it for maximum control. If you do not, you may use the WYSIWYG option (what you see is what you get).
In each piece of content that you create, go below the Body (Edit summary) box, select the Text format that you can use.
Full HTML format will allow text added to the Body to appear as you format it (with color, bolded, etc.).