This mode allows html to be entered directly. The formatting options are thus
far more flexible, but at the price of considerably greater complexity.
If you just need to a few changes to the format of the page, the easiest way
to proceed is to create the page using formatted text, convert it to html,
and then modify the html as necessary.
In this mode, the html should consist of one or more paragraphs, delimited
by <p>...</p> tags. Note that it is quite possible to render your page
unreadable if you use html incorrectly. There are many excellent html
tutorials available: www.w3c.org is one place to start.