If you have any other operating systems on your system that you wish to keep (dual boot setup), you should make sure that they have been properly shut down before you boot the installer. Installing an operating system while another operating system is in hibernation (has been suspended to disk) could result in loss of, or damage to the state of the suspended operating system which could cause problems when it is rebooted.
If your computer will boot from USB, this will probably be the easiest route for installation. Assuming you have prepared everything from Section 3.6.2, “Boot Device Selection” and Section 4.3, “Preparing Files for USB Memory Stick Booting”, just plug your USB stick into some free USB connector and reboot the computer. The system should boot up, and unless you have used the flexible way to build the stick and not enabled it, you should be presented with a graphical boot menu (on hardware that supports it). Here you can select various installer options, or just hit Enter.
If you have a CD set, and if your machine supports booting directly off the CD, great! Simply insert your CD, reboot, and proceed to the next chapter.
Note that certain CD drives may require special drivers, and thus be inaccessible in the early installation stages. If it turns out the standard way of booting off a CD doesn't work for your hardware, revisit this chapter and read about alternate kernels and installation methods which may work for you.
Even if you cannot boot from CD-ROM, you can probably install the Debian system components and any packages you want from CD-ROM. Simply boot using a different medium and when it's time to install the operating system, base system, and any additional packages, point the installation system at the CD-ROM drive.
If you have problems booting, see Section 5.4, “Troubleshooting the Installation Process”.
To start the installer from Windows, you can either
obtain CD-ROM/DVD-ROM or USB memory stick installation media as described in Section 4.1, “Official Debian GNU/kFreeBSD CD/DVD-ROM Sets” respective Section 4.3, “Preparing Files for USB Memory Stick Booting” or
download a standalone Windows executable, which is available as tools/win32-loader/stable/win32-loader.exe on the Debian mirrors.
If you use an installation CD or DVD, a pre-installation program should be launched automatically when you insert the disc. In case Windows does not start it automatically, or if you are using a USB memory stick, you can run it manually by accessing the device and executing setup.exe.
After the program has been started, a few preliminary questions will be asked and the system will be prepared to reboot into the Debian GNU/kFreeBSD installer.