Azuth,
The easiest way to see find new posts is probably to use the "View New Posts" link that is part of the page header (over on the right side). That will show up new posts regardless of what forum, etc. they may be in.
Visually - you'll see that the "ibp" button is dark when a forum has new posts in it and faded when it doesn't.
When you enter a thread with new messages - you'll see a small button with a down pointing arrow just to the left of the topic. If you hold your cursor over this a pop-up will tell you that clicking on this will take you to the unread messages in the thread. [Credit: Thanks to DWillard - He made a note on this feature in another thread and I copied it for use here

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Hope that helps