I'm not sure what it is you are asking.

This is set up using tables. Tables are an effective way of organizing material on a page. However, normally the sender information is not in the "page" of a document but in the first-page header and footer. That may or may not be organized using a table. Putting it in the first-page header means that you can just start typing your letter without worrying about overtyping your letterhead information.

To see the table organization, you need to display the table gridlines. This is under the Table menu.

See Setting Up Letter Templates and the Letterhead tutorials on my site.

You could use MacroButton Fields as prompts for your highlighted areas - places to type. When someone clicks on one of these and types the prompt disappears.

Once a letterhead is designed, it is stored as a Template, not as a document. That way when a new letter is written, you don't have to worry about messing up all future letters with a typo. See Templates in Microsoft Word.