When you open the Quick Start window (File > New From Quick Start), you select the DOCTYPE from the DOCTYPE drop-down list. This automatically inserts a preset block of code into your page. This is all well and good, but what if you want to customize this code? No sweat! Go to Tools > Preferences > Customization > Open Markup Library. This opens the CoffeeCup HTML Editor Markup folder on your computer. Here, you can open and modify the default HTML layouts and framesets for HTML, HTML 4.01, HTML5, and XHTML 1.
Note: You should know what you're doing before you attempt to edit these files! If you don't, you run the risk of messing up the program. Don't worry if you do, though; you can always just reinstall the HTML Editor to restore the default settings.