First tick the box labelled "The descriptions below are in HTML".
Then use the following (you'll need to use the paragraph and line break tags, not just hit "Enter" for a new paragraph, etc.):
New paragraph (for blank space between paragraphs) <p>
Line break (for starting a new line with no blank space above it) <br>
Bold text <b>Text here</b>
Italics <i>Text here</i>
If you want any more tags just shout.
Do not go gentle into that good night.
Rage, rage against the dying of the light. (Dylan Thomas)