If you have average skill using an SDK should be helpful for you.
Start out with something like XNA Game Studio to see how those concepts are done.
This document is the starting point for the SDK https://msdn.microsoft.com/en-us/library/bb200104.aspx and the “Network” concepts you are specially looking for are discussed here: https://msdn.microsoft.com/en-us/library/bb975947.aspx
As for the database for accounts, this would be no different than any typical application that accesses a database and stores user accounts.
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solved How would I go about Game Networking with C#? [closed]