The problem TheBlueDeath is Brawl. With many of the better smashes not really paying attention to the melee forums at the moment a lot of them are getting neglected.
To the OP, if you want to get a basic idea of what to do with Marth. Just watch videos... Your not asking specific advice, just general movement and strategy. Sure their will be many tactics you don't understand, aren't viable for you, and/or out of your reach as a competitive gamer. But hey, learning has to be somewhere in the middle of all of the easy stuff you can do.
And if you don't understand what I meant. It's easy enough to see what good Marth's do, but it's much harder to understand why, then actually implement them CORRECTLY into your game. Only way you can do that is by your own practice and trial and error.