Database Nesting Question

I am building an app that allows for professional traders to create a group by which they post their trades. Each group can be subscribed to by other users. How do I nest the data structure. We have a list of trade groups. A field identifying the Master of each group. A list of users per each trade group. And there must obviously a field that stores the active trade of the Master that is available to the list of users to that group. How may I structure this?