If you are starting from a blank DVD design, make sure "Case" is selected on the toolbar. Click the "Insert" button from the top toolbar and select "Text". A horizontal text box will appear where you can type your information. Next, rotate the text to the correct angle (hold down the left mouse button over the circular selection dot). You will then need to manually adjust the dimensions of the inserted text box to fit the width and height of the spine.
Let me know if you need further assistance.