Html box pro module right after installation process assigns module to necessary hooks (modules > positions section in shop back office). The most important control panel of the plugin is located just on module configuration page. You can manage all module aspects there and manage blocks appearance, remove them, edit etc.

On module configuration page you can find several sections. There you can manage the module (details about module management you can find in the next section in this module documentation). Screenshot attached below shows you how to open module configuration page. To create new blocks with own contents just go there.