Place the motor on the drone arm and line the four motors screw holes up with the holes in the drone arm.

Once aligned, the screws can be inserted to fix the motor to the drone. Also, make sure the motor wires run down the length of the arm and not in some other direction.

If you are splicing the new motor wires to pre-existing ESC wires, then slide new heat shrink tubing onto each of the three wires before soldering the new motor wires in place. If you are soldering your new motor wires directly to the pads of the ESC, you don't need to use any heat shrink tubing.

Now, solder the new motor wires to the ESC or the previous wires. Ensure there are no shorts (undesired connections) between any of the wires and make sure everything is properly insulated when you're finished. If any of these wires short to each other or the carbon fiber frame, it could brick your ESC.