WARNING: it is imperative that you use the provided ferrule connectors for the power supply, hotend heaters, and bed heater.

Failure to use the provided ferrules can result in wire creeping, causing the wires to come loose and can possibly create a short circuit, which could result in fire.

The crimp tool shown in this photo is a basic and inexpensive tool available from any hardware store, electrical shop, etc.

The method of crimp shown here is called an indent crimp. You should ensure that the tool you use provides a tight crimp to the ferrule.

It is also best to use the include Molex connectors for all other connections as they ensure correct polarity and lock into place.