Okay...I'd just like some tips as to aesthetically pleasing color combinations and such. I'm making a banner for Maple Story Mob's contest to win some free NX...and I'd really like to send in something made from a professional stand point. Has anyone here had official training in graphic design?

What I want is something short, simple, and to the point.

I want a character that looks like a noob, and one all dressed up in cash stuff...and have a slogan something like "Stop looking like a noob, Join Maple Mob for some free NX" something like that.

How should I make the layout? I need advice for a background mainly. And font. ANY advice is GREATLY appreciated

Edit: I am a semi-educated photoshop user, so, feel free to use semi-technical terms with me here. I can get any number of tools to use, as long as they are Mac compatible.