They don't mean fork ethereum and create a new currency. They mean create a new currency running on the ethereum platform. A bitcoin fork means you have to build up a group of miners sufficiently large and diverse enough that everyone trusts it. Making a currency on ethereum means it inherits the trust that ethereum has.

Here is the tutorial about creating your own coin on ethereum. It's pretty short and interesting: https://www.ethereum.org/token

People like to think of ether as another cryptocurrency like bitcoin but the ethereum currency is intended to be more like a commodity that is used to fuel the platform that runs all sorts of stuff (including currencies).