Solder your LH and and RH on to each terminal. I then soldered the ground to one of the grounds on the case. there are a few in the same area.
Once you have that done, put it all back together. I used hot glue and glued the wire connection down on the board as well. its a delicate solder joint so you don't want any strain on it.
I ran the cable out the back of my stereo and into my centre console. Now you can plug any audio device into that cable. I ended up buying a Blutooth receiver off Amazon. Mpow was the brand. $20. It connects to my iPhone every time and has good battery life.
For best sound you should keep your phone at about 80% volume to avoid overdriving the audio.
Basically any input you run through that cable will play through the system whether its on tape, radio or CD. I searched for a blank audio CD file online and burned myself a CDR- with a 30 minute blank track on it. Google "Silent CD" . It pays continuously without every interrupting the aux input.
Now I can use Spotify continuously. Not always for actually listening to music, but to have music in the background to drown out those 30 year rattles!