Correct wiring for steering wheel

[Simmons]

Good afternoon
I have just replaced my krc-394 with a KDC-3057.
The unit obviously slipped straight in, however.
The 394 worked fine with the steering wheel controls, the 3057 has a lead marked steering wheel but has nowhere to go.
Any ideas where it needs to be plugged into (it is a bare wire folded back and stickered steering wheel control)

Thanks in advance.