This concept of navigation is fairly simple, you want your users to find information logically and quickly. Make sure that there is a navigation menu readily available from every page. Don't make your users rely on the 'back' button.
Depending on the volume of pages on your site, you may have to make use of a two different navigation panes, that is to say, you'll want to implement a top level navigation menu and a sub-navigation menu. The top level navigation menu is useful for accessing broad, high level topic. The sub-navigation menu is useful for finding your away around the particular area of the site that you're in. If you want to get really fancy, this is where expandable menus and drop down buttons can be utilized.
PSD.Fanextra.com offers some good examples of site navigation. Notice how the bulk of the examples used on that site use a horizontal navigation bar, below the header. This area is typically where your high level navigation will be held. If you need a sub-navigation menu, you can make use of an interactive menu which drops, or expands accordian style, but if you don't have the skills, experience or time, you can place a sub-navigation menu on a side column.