What is the purpose of the page guides? Are they pre-set to define where I should put my content so that it will show as intended across multiple devices? When I start a new page, they are there and basically split the page into thirds. These means that the center section is rather narrow. But, I am concerned that if I adjust them, I will be messing something up.
Everything between those two page guides are always centred and determine the size and positioning of the content on your page. You can adjust those page guides, but just make sure you re-align the elements so they are aligned or centred to the new width.
That said I would advise against sizing the page width/guides larger than 1000px. For customers with smaller screens having a large page width means they have to scroll left/right to read the content of your page.
Awesome, thanks Johnny. I set them at exactly 1000px and things look great!