Headers normally appear on every page in a document; this distinguishes them from any other type of heading or title. If you place a header on just a single page, Google Docs won't consider it a header at all. But it will still act as a header in every other way, listing information such as the document's title, author and publication date. One way to insert this emulated header is to use a text box using Google's Drawing tool.
Click "Insert" in your document's menu bar, and click "Drawing" to open the Drawing pane.
Click the text box icon in the pane's toolbar. Click and drag over the canvas to create a text box.
Type the text of your header, and press "Enter" to add it to the drawing.
Format the text using the toolbar's Font, Size and Style buttons.
Create additional text boxes if you want your header to include multiple pieces of text.
Click "Save & Close" to insert the drawing into the document. Click the header and drag it to the top of the document's first page.