[RWebb]

how to tap? into a terminal or into a wire?

terminal is easiest - get a single to double Faston and yer done

for tapping into a wire, there is a columnar shaped thing with prongs - it unscrews and you enclose the wire in it; screw to pierce
- then you put the add-on wire into the other end and screw that down

wish I had a p/n or pic handy but hope that helps - ones I have are yellow