Widget Area in Header

How would you create a widget area in your header.php file so that you may put widgets there? In particular, many sites show the log in at the top right corner of your home page.

If you are using child themes, you could edit the header.php file, but what code do you need? Th3e code is a two step process. First you add code to your functions.php file to identify and name your locations. You use the function register_sidebar(). The next step is to assign the HTML real estate position to this widget area. See page 271-72 of the Wrox book Professional WordPress, Third Edition.