@garybrantley,
iModeler is quite different from a "classic" discussion forum, so the concepts may take a moment to understand.
The first concept is that this is a crowd sourced site. We follow a general principle "If you can see it, you can contribute to it."
There are three main parts of the site where you can post stuff.
Headlines - anything you would like the entire world to see. Typically your finished models, your work in progress, kit review you make, walkaround of a favorite aircraft etc. Headline articles offer great photo support an exposure at the front page, meaning being shown to everyone visiting the site. Headline articles are being routinely reviewed by the editor to avoid any mishaps, and also participate in our monthly contest.
Activity - this is the log of everything happening at the site. Most users will simply be checking it as a "what's new" page, but you can also add short text messages or chat with your friends.
Groups - these are special interest groups where you can debate any questions in a narrower setting. Groups are usually started by members for other members around a certain subject. Groups offer great facilities for general discussion (including, for example, daily email digests etc.) but provide only simplified photo support and of course, your messages will only be reaching a more targeted audience.
My stuff - this tab simply groups together everything that you have posted across the site. Efficiently it doubles as your personal blog and yes, you can also add articles directly from there.
Hope this helps
/m