SiteBuilder has a panel in the bottom of its editor window where you can see the underlying HTML structure.
HTML, or HyperText Markup Language, is a standardized language for presenting information, graphics, and multimedia on the World Wide Web. Although SiteBuilder does not require the knowledge of HTML from its users, those knowing it can benefit from this by using this panel.
While editing a page in SiteBuilder, you can place the text cursor anywhere on the page. Different areas of page have different styles and contain different types of information. The left side of the bottom panel shows in which area the cursor is located. So, when you place cursor, for example, in a table, the bottom panel will reflect this. The name of the active block is shown with the bold font. You can click on a tag in the list and the corresponding area will be selected in the editor as if you have selected it with the mouse.
For each area you could edit some of its properties by clicking the Advanced button at the right of the panel. A window will appear where you can set some parameters such as colors of the block and properties of its border.
The Properties button appears only for selected types of blocks: TABLE, A (Link), UL (Unordered list), OL (Ordered list), IMG (Image). For each type of block, it allows to edit some properties, specific to it. Often, they coincide with the ones you can setup when inserting the corresponding object (table, image). In other cases, their content is unique, like in the case with ordered and unordered lists.