Locating Your Template.html File
You can find your store's template.html file at Design > File Editor in your store Admin Area.
On the File Editor page, you will see several links within the Shortcuts table on right side. Click on the template_xx.html link to load the contents of your Volusion store's theme file into the File Editor (where "xx" is the name or number of the theme currently active on your store).
Changes made to your template.html file will not be carried over to other theme files if you switch from one theme to another.
Locating Your Template.css File
In addition to your store's template.html file, there is also an associated template_xx.css file associated with each design theme. This file will contain the majority of CSS definitions that control the overall look of your Volusion store's theme. Click the template_xx.css link on the right side of Design > File Editor to view or edit your store's CSS files (where "xx" is the name or number of the theme currently active on your store).
See "How to Add, Edit, or Remove Footer Links from Your Theme" for additional information.