From me, it will be very, VERY basic.
The controller works like a switch. Speed is controlled by turning it off and on. Full throttle is on all the time, half throttle has it off some of the time. The switch is very fast, so the motor just has less power, but it doesn't really start and stop every time the power is off.
Brushless controllers then split that power signal among three wires. Timing of when the power is on on each wire makes the magnet attract to one spot, followed by the next one, and the next, causing the motor to spin constantly trying to get lined up with the next magnet. Most motors have hall sensors, that tell the controller when the motor is in which position.