I downloaded and installed the Nukes alpha w/ 3.2.1

I want to create a message forum where users can post, read, and reply to messages.

Is the "section" area used for this purpose?

After creating "sections", I don't see how a user can post a message. And the "articles" that I entered as user admin do not show up when I view the section
as a newly registered user.

I'm also seeing broken links ex. "/images/sections/transparent.gif"

I unpacked the ear and war but did not find where the graphics are stored.

Any ideas on the broken links and posting messages.