Themes allow you to override the core, so you can make changes to a website without putting the core at risk. Every module has default templates to start of with, though a theme can override each and everyone of these default templates. This, however, doesn't mean you have to overwrite the entire core. You only overwrite files that will make a difference.website4free system will detect all the files in the template folder.
If you put the filestructure of the core and a theme side by side, you'll see that these resemble each other. This should give you a further insight in how themes work.
The template directory structure should be
Contains different layouts of web pages.The template files are
a)one-column-full-page-width.tpl - no panels
b)two-columns-left-menu.tpl - panel will be left side
c)two-columns-right-menu.tpl - panel will be right side
To handle aside panel and will be included from here. It has
a) aside.tpl - for displaying the aside content
b)messages.tpl - for displaying messages like success or success
includes/widgets Module specific widget templates will be handled here.
footer.tpl Displaying footer content
header.tpl Displaying header content like top navigation and breadcrumb
page_start.tpl Page meta information, stylesheet includes etc...
page_end.tpl Script includes, extra footer content etc...
404.tpl page not found template file
main.tpl This is the main tpl which includes all necessary layout, panel and module content  and finally will render as website page.
module folder
Module specific template files

It will be very easier to develop the new template, if you copy the existing default template provided by website4free system.

Please use the following link to download the default template.

Download sample default template