Inserts are two up on a letter size page, put two front pages on the upper one and two back pages on the lower one. Save as a pdf for high quality print.
To use the pdf template, download it, pull it into illustrator or photoshop on it's own layer, then after you create your artwork, turn off the layer with the template on it and save as pdf for 'high quality print' or as a .jpg Be sure to bleed the background art or layer out over the edge by about an eighth of an inch.