No. If done correctly, there will be a folder named (for example) includes/templates/NEW_TEMPLATE, and in that folder there will be a file named template_info.php. Zencart looks for that file and adds the template name specified therein to the dropdown in the template selector.

If you aren't seeing the new template in admin, that file isn't where it needs to be, or isn't complete.

What template is it, and where did you get it?