You've assembled your robot and can now control it via the BeagleBone Blue. You can run the control program using a VNC server configuration. Doing this will allow you basic control of the robot wirelessly. However, it would be easier to control your quadcopter using a game controller.
What you want is a controller that has more immediate control of the different aspects of your robot. Perhaps the most practical is a game controller that has two joysticks and several additional buttons. Using these as input mechanisms will make controlling your robot with the BeagleBone Blue much easier.
To add the game controller, you'll need to first find a game controller that can connect to your computer. If you are using Microsoft Windows as the OS on the host computer, then pretty much any USB controller that can connect to a PC...