A friend of mine says whenever she gets on any internet site on her Blackberry 8830 "the site is huge and not the mobile." How does she change that?

If the site isn't optimized for mobile devices, there isn't much one can do.

To really help with a solution, we need a lot more info.

Which browser is she using?

What sites?

Define "huge"

Assuming that she's using the built-in browser, setting the browser emulation to Blackberry might help. However, a web site has to be able to detect the browser and offer a mobile version (not all do).