This topic is divided into sections describing the procedures needed to produce and install trusted software. For background information, you may want to read Administering users and groups and ``Introduction to security''.
It is a good idea to become familiar with the background material first, then proceed with reading the sections that explain how to ensure trust in the kind of software you are writing. Reading all the sections is useful, but not essential. Many rules for ensuring trust are also good general programming practices, so they may also benefit any programming you do.
Finally, be aware that these sections does not contain the definitive explanation of trust. Writing software is as much an art as it is a science, and the rules presented here are only guidelines to gain an understanding of the issues involved. It is by no means a guarantee that you will produce trusted software if you blindly obey the rules and dutifully mark the checklists. However, reading the advice here is a good beginning to learning how to write trusted software.