The page layout section is shown to the left of the Cell Editor:
It contains the following elements, each of which is documented separately:
• Toolbar
• Cells (Pre-built or HTML template)
• Tabset
Each is covered separately.
More:
Page Layout – Toolbar
Choose Page Layout Dialog
Page Layout – Grid
Page Layout – HTML Template
Page Layout – Tabset
Page Layout – Page Tab
Page Layout – Cell Tab