BLDC motor or brushless motor are little bit different from normal Brushed motor. You can power it directly from Battery like a normal dc motor. So to run a BLDC motor you need some items.
ESC (Electronic Speed Controller)
This is a pic of ESC of 30A rated.
Now this one is servo tester.
Now We are using a 1800 kV bldc motor of A2212 series.
We are using 2200 KV Lipo battery to power the motor.
Now Connect the ESC three wire directly to the Motor Three wire. If you do cross connection the motor rotation will be reverse. On servo tester you found Signal pin. On that you need to connect the esc signal pin. Remember Yellow for Signal pin, red for positive, black for negative. Now connect the battery to the ESC.
MAKE SURE THE KNOB ON THE SERVO TESTER SHOULD BE IN ZERO POSITION. otherwise motor will not start. SO after connection there will be some sound like "bip bip." After that you rotate the knob of servo test to control the speed. If you rotate the knob full then you get full speed from the motor.