Page Layout
When you first open a CDman template for a booklet, you will notice three colored lines. We have selected Red, Green and Blue colored lines.

RED LINE : Like in baseball the warning track warns the player that they are getting close to smashing their head into a wall. This warning line is telling you to keep critical text and images inside this line or risk getting them cut off.
BLUE LINE : This is the wall. A hydraulic blade comes smashing down on 1000 sheets of paper cutting the panels from the press sheet. Also called the final "trim" mark.
GREEN LINE : This is the bleed line. Often misunderstood, you must think about the hydraulic cutting blade to understand what bleed is for. When you have 1000 sheets of paper stacked up on top of each other and a cutting blade slicing through all those sheets of paper, there is bound to be a degree of slippage by the time the blade gets through all the sheets. It can be as small as 1/64th of an inch, but this small amount can leave an unsightly white line running across your page.
Bleed

In the above image you can see the booklet (page) was cut without the designer adding bleed.
(Booklet was placed on a black mat for illustration purposes)
Solution: If the designer had stretched the orange background to the green line of our template, then even if the cutting blade had been way off, there would be no white line since there is plenty of safety margin or "bleed". Simple solution, but important.
Gatefolds vs. Wrap Folds
A Gate Fold (above) has the two most outer panels fold inward first and then the resulting "gate" is then folded once more to make the final 5" square.

A Wrap fold (above) is what most designers use for long spreads. It is most common to use a wrap fold.