I am trying to find the feature to add a page template. I am adding an archive but when I go into pages->Add New-> I get no option in the sidebar to use the existing archives.php file I want to use. Can anyone help me out?
archives.php is a template file that WordPress will use by default (if it exists). If you want to create a custom page template you need to create a new template file in your theme. You can read all about it in the Codex, but I'll provide an example below. Put this at the top of your new file:
<?php /* Template Name: Your page template name goes here. */ ?>
Then follow it with the custom code you need to display your data.
Then, when creating a new page that you would like to use the above template, you will see a drop-down list on the right that lists all the names of page templates you have in your theme.