Computer Security: The NIST Handbook

If you are new in Computer Security field and need to learn on how to provide security for your company working environment. I highly recommend you begin reading the Special Publication 800 series e.g. The NIST Handbook.

Special Publication (800 Series)
Special Publications in the 800 series present documents of general interest to the computer security community. The Special Publication 800 series was established in 1990 to provide a separate identity for information technology security publications. This Special Publication 800 series reports on ITL's research, guidelines, and outreach efforts in computer security, and its collaborative activities with industry, government, and academic organizations. (NIST.GOV, 2010)

To start, read the Special Publication 800-12 An Introduction to Computer Security, and follow-up with other reading materials where your current responsibility fit. For example about Cryptography, read Special Publication 800-21 2nd Edition: Guideline for Implementing Cryptography in Federal Goverment, or SP 800-30 for Risk Management Guide for Information Technology Systems, or SP 800-44 for Guidelines on Securing Public Web Servers, or SP 800-45 for Guidelines on Electronic Mail Security, etc.

The Special Publications 800 Series will give you enough information to start your study and documentation.

References:
An Introduction to Computer Security: The Nist Handbook
Special Publications (800 Series) http://csrc.nist.gov/publications/PubsSPs.html
An Introduction to Computer Security: The NIST Handbook http://csrc.nist.gov/publications/nistpubs/800-12/handbook.pdf