Get the .iso File

Download the preseed.iso file.

Brave? Try the Sid pre-seed .iso.

Burn the .iso File

In Gnome, right-click the file to burn it to a CD.

In KDE, use K3B to burn the file.

In Windows, use the built-in utility or an add-on program like Nero.

If you are going to test the .iso in a VM, you don't need to burn a CD.

Boot the CD and Choose Your Desktop

Answer the Language and Network Questions

The installation will download and install the base system, partition the first disk (completely destroying all data on it), 

Answer the User Questions

Reboot into Your New System

Your new system will come complete with Flash and Java plugins, restricted codecs, and extra fonts. Enjoy.