When you start Word, you see the page in print layout view. This view shows the document as it will look when you print it. For example, you can see the white space around the outside edge of the page that makes up the margins. Also, you see a gray space at the top, bottom, and sides of each page. If you have a multiple page document, the gray space separates each page.
You can also look at the page another way on the screen: in normal view. In this view, you don't see the margins (or the gray space around the page), you just see the body of your document. If you have a multiple page document, the pages run continuously, separated by a dotted line at the end of each page.
You can type in either view. It's up to you to decide which view you best like to work in. If you work in normal view, it's a good idea to switch to print layout view to check your document out at least once before you print or send your document to someone else. There are some elements you can't see in normal view. For example, some graphics do not show up in this view.
You switch views by clicking the View menu. You can easily go between both views as you like. You'll see how in the practice.