Questions about code signing

[Michael_google gmail_Gersten]

>> I have no idea how code signing works.
>>
> You must have read the docs.  It was a simple idea until I did that :\

ouch. My Brain ...

codesign. csreq. certtool. systemkeychain. security. taskgated.

Is there a simple introduction to security on Mac Os that actually
deals with this? I found the "How logins work / brief description of
Linux Pam on Mac OS" intro, but nothing for this.