Each page has a half triangle on the side and bottom/top of the page. These match up to the corresponding page so that you can fit pages together accurately.
Start laying out the first row of 5 pages following the large page numbers. Lay out the next 5 pages in a row underneath and so on.
On the borders, cut accurately along the top and left hand side line on each page. Some pages does not need to be cut if no pattern piece connect.
Use tape or glue to put the pages together.