Can wiring gurus please help me figure out which terminals to solder my LEDs to?

I've done soldering before and I'm comfortable with it, I just can't identify the positive and the negative terminals to use.

This is from my 2006 triple HUD gauges










Indeed I did read through the thread called "Interior LED Conversion". I pulled this bit of information from there, but I still can't figure out where the positive is located.