Place the fully functional WordPress login or registration form anywhere on your website using a widget, or a shortcode.
Widget Settings - These are the settings that you will see once you drag the widget into your sidebars
Login Form - Here's how the login form displays on the default twenty twelve theme
Shortcode Settings - These are the settings that you will see once you click on the shortcode icon in your WYSIWYG editor
Shortcode Icon - Here's a red arrow pointing to the shortcode icon that you should look for in your WYSIWYG editor