Since Linux is a collaborative development environment, everyone that has contributed to the project has usually written some of the documentation.
The users and developers.
Members of the Linux Documentation Project. Individual package maintainers write manual pages for their software.
every one who likes to help linux
Mario Sevilla
government
By configuring the bootloader to use Windows as the default menu option instead of Linux. Refer to documentation on how to do this.
Many distributions have documentation or builtin graphical installation utilities.
Linux was created in 1991 by a Finnish college student named Linus Torvalds.
The 'man' or the 'info' command have documentation about utilities and commands in the system.
Man (or manual) pages
Most screensavers on Linux are modules run by Xscreensaver: http://en.wikipedia.org/wiki/XScreenSaver I don't know exactly how to convert a program to a module, check the Xscreensaver documentation.
The Linux kernel was originally written by Linus Torvalds (Linux is only one letter away from Linus) Over time most of the Linux kernel has been modified by many people in the open source community, however Linus still oversees the project.