works: MIDI-IN: code + schematics

Hi all,

I had a few questions.
I'm using some software to send midi data from the pc to a midi kabel.
I'm still confused about the pin's. I don't know if i'm mixing them up.
"putting an LED between pins 4 and 5 of the jack"
seems a good way to figure out which pin is four and which is 5.
what way would the current flow?

Should the led light up like this:
4 Cathode,
5 Anode

or like this:
4 Anode,
5 Cathode??

And what about channels? will this work with all channels? or: How to set channels?

I hope you can help me!

Titus