Accessing the control panel is done via logging in Joomla!'s back end. Upon log in, you are looking at the control panel. If you want to access the control panel from another area in the back end, simply go to Site > Control Panel.
The control panel provides access to many default Joomla! functions and features. It allows you to create a a new article. You can also manage existing articles, sections, and categories. Also available at the control panel is the media, menu, and language, and user managers. Finally, you can access your site's global configuration settings.
In the table with .... displayed, you will see different columns. Here you can read what they mean and what is displayed in that column.
Using modular templates; Column_headers_helpscreens
The functions are:
Using modular templates; Toolbar_helpscreens