creating new templates

I am sure this is very basic .. but I can’t seem to figure it out .. I have created various templates with specific layouts and queries I want .. but how do I link to those templates/pages?

For example say I created the following pages with specific queries and layouts

show_only_category_1_and_20.php
show_10_excerpt_posts_with_thumbnails.php
show_10_full_posts_with_thumbnails.php

How to I pull these up?
I thought it would be something like
http://mysite.com/show_only_category_1_and_20.php
or
http://mysite.com/show_only_category_1_and_20/

but that doesn’t seem to work?

Thanks