There are spots there for you to set up your left margin your right margin and your gutter.
Explain inside outside and gutter margins.
That is what you see in the photo.
The gutter margin is a typographical term used to designate an additional margin added to a page layout to compensate for the part of the paper made unusable by the binding process.
Top bottom and outside margins and a 1 25 inside margin or a 1 margin and a 0 25 gutter on your portrait pages.
Inside margin is in big way affected by the way the publication is bound and by the thickness of the publication.
In a facing pages layout word refers to this type of layout as mirror margins the gutter margin is on the very inside of both pages.
This particular book happened to be fairly thick 356 pages so i set the gutter to 0 3 inches.
This creates a gutter where the two pages join.
Outside or for edge margin.
The reason for this is that books do not lay flat when they are opened.
The pages have to bend out from the spine.
By convention landscape pages whether recto or verso are oriented with the top of the page to the left.
However one of your margins will need to be bigger than the others and that is the inside margin otherwise known as the gutter.
To make it easier for the reader to read the text you should prevent the type from hiding in the gutter.
A standard is to set the left and right margins at a half inch each and to then have a quarter inch gutter.
As the pages disappear towards the binding the.
If your publication is very thick you should make inner margin wider than usual.