Clicking the Split button lets you see both the Code and Design windowsBefore you do anything else, save your document. It is always a good idea to save a new HTML document in Dreamweaver in the directory that houses your parent Web site before you begin coding. This will help avoid broken and misdirected links later on if you decide to link to internal site pages.
Dreamweaver lets your author a page via its WYSIWYG tools as well as by hand-coding. Its best to have both options visible at all times so that you can switch back and forth and see how modifying the code affects the browser preview and vice-versa. If both the Code and Design view are not visible, click on the button that is labeled "Split". You will find it in-between the Code and Design buttons near the top of the screen, under the document tab.