Question Creating custom classes

[Tricent]

So yeah, I've explored building the private server and well I've played on a few before.
What I've noticed is that there needs to be something special about the server, something that'll catch people's eyes.
I was thinking with my server that I could perhaps add some new classes, nothing big and hopefully not overpowered. If worse comes to worse I'll just remove them.
I was wondering if there'd be any software that I'd need for scripting the characters and stuff.
Please help me out.