In FeedDemon, a news item is a single piece of news, such as a story about a current event or an entry in a personal weblog. News items are displayed in the news item list, which appears in FeedDemon's second panel.
When you select a channel, the news item list displays all of that channel's news items. By default, the description (content) of each news item is shown, but you can change this by clicking the 
"Show descriptions" toolbutton.
News items default to being grouped by the date they were received (downloaded), but you can choose another grouping through the "Group By" selection. If you'd prefer not to group news items, simply select (none) from this list.
Normally you'll want to see all news items in a channel, but there may be times when you'd prefer to see only items containing a specific word. To do this, click the 
"Show filter bar" toolbutton, then type a keyword in the filter bar. Only news items containing that keyword in their title or description will be displayed. To clear the filter, either delete the keyword or select (none) from the filter bar dropdown.
Individual news items may be flagged by clicking the 
flag icon that appears to the right of the item. A flag is simply a way for you to mark a news item for later reference. If a channel contains a large number of news items, you may find it helpful to flag the most interesting news items so that they're visually separated from the rest of the items.
Note: If you discover yourself flagging a lot of news items, you may find it more useful to store the items in a news bin instead.