Fusion 360 is a program that allows you to design in a parametric 3 dimensional environment and also provides a great CAM toolset. Fusion 360 will produce the gcode with the CAM capabilities. The gcode is used to move the machine in various ways in order to mill the material; however, software is needed to interpret this gcode and cause the machine to move according to the gcode instructions. This is called control software. So Fusion is CAD/CAM, and you still need "control". Mach3 is one example of control software for milling and is highly recommended.
Install Mach3 onto the computer that will connect to the redFly(CNC electronics), then configure the Mach3 parameters for the machine (motor tuning, plug-ins, inputs/output, etc.). Home the machine, load the gcode into Mach3 and the machine will move according to the gcode.
A word of caution, since you are new to CNC machines, make sure you familiar yourself with the machine and the movements of the machine specific to how the gcode is arranged with respect to the coordinates of the machine. Try with very simple gcode until you get a very good understanding of how the machine will move.