i was wondering if someone could help me with ohms n stuff on heads n cabs, which ohm input on head goes to which ohm input on cab, i just got my first valve head and hope to be using it for my school music exams in a couple of days with my friends cab, any help would be much appreciated.
You match the resistance (ohm) of the cab to the head.

So if your cab is 16 ohm, you plug into the 16 ohm jack on the head.

If there are more than one it usually doesn't matter which is which. Some amps have stereo out, though, so in that case you'd want to plug it into the one marked MONO.