Can you provide more detail on what this “archive-only page” is?
If you mean a Page (Write > Write Page) in WordPress intended for displaying your archives, this may help:
http://codex.wordpress.org/Pages#Page_Templates
Otherwise, assume we do not know exactly what you want and explain.
I copied arc-cont.php page from the example on the link you provided. I just need to know how to visit the page now. I mean, when I try to use the url mywebdomainname.com/wp-content/themes/themename/arc-cont.php it doesn’t work.
Please return to the link I provided above and read what it has to say about assigning a template to a Page.
