Debian GNU/Linux is distributed freely over the Internet. You can download all of it from any of our mirrors.
If you simply want to install Debian, these are your options:
Several different types of images, including CDs and DVDs, are
available for download, including small netinst
CDs that can
quickly be downloaded.
Many of the vendors sell the distribution for less than US$5 plus
shipping (check their web page to see if they ship internationally).
Some of the books about Debian come with
CDs, too.
Here are the basic advantages of CDs prepared by someone else:
There are a number of advantages to this:
The Installation Manual contains detailed installation instructions.