Guidelines are on by default in CreativeStudio. They serve to show you where the outer bounds of your design reside in relation to your product. For example, please see below. The image on the left has guidelines turned on, whereas the image on the right does not. As you can see, designing with the guidelines turned on provides for a much easier experience. Turning the guidelines off will allow you to get a more accurate depiction of your creation.
To turn off guidelines, select the Guidelines option above your design. To turn them back on, click the Guidelines option again.