no you are not grasping this yet
you are not making a new theme
you are adding one custom page to your existing theme.
that custom page has to be associated with specific wordpress static pages in the WP editor.
go into the wordpress editor and create a page on which you want the content to display with no sidebar or footer
To the right of the edit window is a section called Attributes.
There is a pulldown in that section labelled Template.
In the pulldown you should now see “custom”. select that and now update the page. Now, any content you enter in the editor on that page should display ON THE WEBSITE with no sidebar or footer.
You will still need to make a CSS adjustment to have your content column be as wide as the full page width since it will be leaving space for the sidebar that is not there.
In the custom template you made I suggest setting up the content line like this <div id="content" class="wide">
then you can assign CSS to #content.wide that will override the normal css for #content – there you can make it 800px wide or whatever you need.
#content {
...
width: 550px; /* this will be overriden by the styling in the next group */
...
}
#content.wide { width: 800px; }
