The full Guide on using Moderan with Microsoft Dynamics 365 Business Central is available here:
http://apps.itera.ee/apps/moderan/docs/en-US/help.html
NB! This is applicable only to the Moderan app used for Microsoft Dynamics 365 Business Central. If you have any questions on using Moderan with NAV/Navision versions, please reach out the online chat support or email us at support@moderan.freshdesk.com