This portal talks about system installation. Technical language may be used.
If you want to know how to install Debian in the simplest way, see QuickInstall portal. Here you will find advanced articles.
DebianInstaller - All you need to know about Debian Installer
Calamares - distribution-independent installer framework used on the Debian LiveCD
FAI - Fully Automatic Installation
MiscInstallTips - Additional and technical tips about Debian installations
SystemBuildTools has a list of tools to create install images and other installers