Left hand (the female plug) goes in the 3 pin cd plug, the top right goes into the cd and the one below connects to the to the interface, you can get another plug if yo like or you could omit the bottom one and just solder the interface to the lead.

The plugs (male and female), fit each other.

__________________
Sept 03, M3, Silver Grey. Retro-fits: Modded Mk4 DVD Drive, OEM Bluetooth, VR Control, Rainbow Speaker Upgrade, Sony SOT Amp, HK Sub, CCFL, Intravee II, NightMode.