Coding a Dedicated Server and Client

Hello! I have made a dedicated server and after I made it, I was wondering how do I make the server, and how do I make the client. Do I just make the client on the server including user interfaces? Also, in my game, I have made a button that once it is pressed in the Main Menu User Interface Widget, the button will join a game. My server is also in AWS. Is there any way to do this. Thanks for any help!