For websites with modest content needs, one can directly import Static HTML content chunks into the CMS. The Static chunks are independent HTML files that only contain the content of interest. The common page code is in the templates, while only page speicifc HTML content is in the static HTML file.
These files are typically found in /html/static website folder. You can access tis via FTP or Template Manager.
Any change to the template should be communicated back to the developer because when there is am upgrade the site, the developer may overwrite your templates with the version they are in posession of.
If you wish to change the template, like header, footer etc. please refer to CMS Template Manager