Add an new category

I Want to add an additional category i.e. "News"-category. Which steps are to solve to achive this?

Hi!
By default, there are two menus always visible on your screen, the "Main" menu and the "Top" menu. To customize any of them you have to go to the page Appearance => Menus and set the created menu as a main/top menu. Here are the intelligible instructions:
http://codex.wordpress.org/WordPress_Menu_User_Guide.