My document size is US Legal paper size (14 X 8.5 inches). I've chosen that setting under the page setup. In the viewer window, I can see that there are what seems to be preset margins, and my design content does not fit in those margins. What are the margin inches, so I may design within them? Or is there a way to manually set the margin sizes on an Adobe Illustrator CS6 document?
On the print options page, choose 'Page Setup' then change paper size to US Legal (14 X 8.5 inches). After, go back to 'Print Options', view the drop down menu under 'Scaling'. Choose 'Fit to Page'. There is no need to change margin sizes, this will automatically fit your content within the size of your art board, in this case, 14 X 8.5 inches.