Registering a new dimension

Hello, I am looking to make a new dimension and have no idea what I'm doing; well, mostly no idea. The only thing I have is this, and I can't get my head around what to do. This is in my main initialization event.

		int myworldid = DimensionManager.getNextFreeDimId();
	MyWorldProvider mwp = new MyWorldProvider();
	DimensionManager.registerProviderType(myworldid, mwp, true);
	DimensionManager.registerDimension(myworldid, DimensionManager.getProviderType(myworldid));

I also have this very basic world provider;

package uk.co.toomuchminecraft.sabermod;

import net.minecraft.world.WorldProvider;

public class MyWorldProvider extends WorldProvider
{

@Override
public String getDimensionName()
{
	return "MyWorld";
}

}

What do I need to do to make a new dimension?