Database design to be build fo a secure web-enabled role-based system/forum

It is required to build a database design (3NF - Third Normalization Form, Database Schema, Security, appropriate data types and validation, clear ERD, referential integrity implemented, enables roles to be implemented and create a list of all the data that need to be stored in the database) for a secure web-enabled role-based forum for collecting ideas for improvement from staff in a large company. The system has specific specifications which will be shared at a later stage.