how to solder in a diode

Not sure why you need it.........but. the band on one end is called the cathode. If you look up a generic diagram, the band matches to the end opposite the arrow

like so, the band would be in the right hand end of this diode



Conventional electron current flow is thought of from negative to positive, so current goes AGAINST the arrow.

what this all boils down to is, you would wire this so the band is toward the MSD box, the unbanded end towards the power supply voltage