A clip cord has two ends, one with a standard jack connector and one with “clips”, with the former being the one that goes into your power supply.
The other end has two metal prongs which stick out in opposite directions, usually connected by a spring in the middle. You’ll need to squeeze the two ends together to fit them both through the designated holes in the frame and binding post of your machine.
On most coil tattoo machines, the positive (+) end of the clip cord should be facing downwards and connect to the binding post, while the negative (-) end faces upwards and connects to the frame. Most clip cords will display a difference between the two ends - this is especially important to follow due to the polarised capacitor on the coil machine.