The Wizard has summed things up nicely, but I will add a couple of things:

1. Stay away from short-sleeved dress shirts for more formal events (unless you're wearing a jacket over it) -- I personally do not like them (except on more casual shirts for summer time), but unless you're in uniform (like a pipe band in summer kit), the short-sleeves look "odd" with a tie.

2. I also don't like white dress shirts, save for more "formal" dress, like with an Argyll or Charlie jacket. For what you're wanting to do, a nice sage-green coloured dress would do nicely. a plain black tie would go well with a black belt and black shoes, but I like more "daring" ties. I usually wear "Regimental Stripes" or emblem ties -- I have a beautiful tie from Brooks Brothers with Blue-and-gold fluer-de-lis (for my wife's French heritage) on a green background that almost matches the green in my kilt.

What is the event exactly? That might help us more.

Cheers,

T.