Need help with Multi-threaded programming using C++

Need help to implement an online system. The system should support safe parallel updates to the inventory database from both the supplier and customers on one or multiple items. Customers and Suppliers should be implemented using different threads and all executing in parallel. Requests are received over the internet from suppliers and customers from different computers and would be handle by independent threads on the inventory database and should be done with proper synchronization. The supplier should be able to add/delete deals.