Need to display lower level pages

I tried some searches before posting, but couldn’t find an answer. This seems like such a noob question, so please be gentle …

I’ve set up my site without any trouble. One of the key features of what I am doing requires several levels of pages in a rather extensive tree structure. I expected the lower levels to display when I click on the upper level. So if the top level of pages is A, B, C, when I click on B, I expected B1, B2, and B3 to display. Instead, the site still shows A, B, C. In short, there is no way for me to get to the lower levels of the hierarchy.

I am using Garland. Is this a problem with Garland? If so, does anyone know of a Theme that works the way I want it to?