Creating Security Levels in Access 2007

[MacroScope]

I have done a lot of design work in Access over about 18 years. I'm very good with logic and getting Access to do just about anything I've ever asked of it, but I've never had a need to use security levels before so I'm completely unfamiliar with how to define and utilize them.

I'm building a brand new database, as mentioned in a previous post, to track 3,000,000 shares of a company's stock offering. Nothing has been done yet. It's still conceptual.

Can someone offer a good link or other reference that will give me details of how to use security settings effectively? I would like to do this before anything is actually created.

Thanks in advance to all.