At the moment, Themes have to be manually uploaded to the /impresscms_root/themes directory.
Uploading the files adds the theme to the server, and makes it possible for the system to work with the theme. In order to use the theme in your ImpressCMS site, you need to make it available.
Making themes available
In the General Settings page in the administration menu, just below the selection of allowed themes, you can find a drop-down list that lets you choose the default theme for your site. A visitor that arrives for the first time on your site will be presented with that theme.
Theme selection block
The theme selection block is one of the blocks that are available on every ImpressCMS site. When enabled for your user group, it allows you to choose the theme you want to view the website in. The list of themes that are available in this list are managed on the General Settings > selectable themes page in the control panel.