Hello Joesi,
Sellacious dashboard is the only way to add a product in sellacious. if you are referring frontend as
https://www.xyz.com it is still under consideration whether to support it or not.
As creating product require lot of information to be filled thus seller will login into
https://www.xyz.com/dashboard (where dashboard is sellacious dashboard) seller will see the only information he is meant to see, you can control it from permissions (
https://www.xyz.com/dashboard login as admin and in left menu under settings you will find permissions)
Let us know if that works for you. I am always available on skype and whatsapp if you need any further support.
-Regards
Abhishek