Simpliest way to add a ref field to News ?

Hi evryone,

My client sends me news to add to his website with a ref number. For now, I'm using subtitle field which is not used in FE template.

But what should be the simpliest way to add a little text field "Reference" in news module ?
I only need it in BE (list and detail).

Thanks in adavnce;

Is relatively easy. You can find everything in the documentation.