"Panes" are areas on a page into which modules can be placed.
"Containers" are decorations around modules.
So, you place a module in a pane on a page. You specify a container to style the module. Think of a container as a decorating wrapper for a module. Containers also provide items like "print" and the expandable visibility controls to the module.
To answer your question, yes. You can modify a skin to add additional panes. I'm not sure why you might want to do that, though. Typically a skin may have these sorts of panes:
- A "banner" pane above the menu for banner ads, or other content
- A "top" pane below the menu that extends the width of the page
- "Left," "Content Pane," and "Right" panes -- this is usually the main content part of a page with most of the content going into the central "Content Pane."
- "Bottom" or "Footer" panes at the bottom of the page. This spans the width of the page, and usually would appear above the page footer.
Other alternative will use only two panes in the central part of the page with a left or right pane and a main content pane.
I prefer not to add lots of panes. Instead, on the occasions when you need a non-standard "pane" layout, I like to use ZLDNN's ModuleWrapper module. Esstentially, you can use it to create a "table of panes" inside of an existing pane, and you can set these up to your liking.