Ok, so I bought a randall rx120rh head and rx412 cab combo online. I also bought a monster 16 gauge speaker cable. It finally came today, and I've never owned a half stack before, and i figured it would be simple to set it up, but there's two different places to plug it in and i don't want to blow anything up, and the instruction manual is not helpful.

there's what the back of the head looks like, and below is the cab:


so which spot on the head do i use so i don't blow my cab up?