Do not try to follow instructions directly from the Handbook:Parts namespace (or any of its sub-pages). Handbook:Parts is a meta handbook used for transcluding text. Use the architecture-specific Handbooks found in the Handbook list.
On request, each part of the Gentoo Handbook as a single page as well, which makes it easier for printing.
However, this has the consequence that the links used in the handbook are not going to work properly - instead of pointing to sections later in the "full page", they will refer to the separate pages instead.
Also, a one-page full view of the entire handbook is not possible due to constraints on the wiki itself.