How do I find Uniworld?

I cannot locale a roll call for Uniworld and the River Countess?

can anyone help me please

Because of the small size of the ships there are rarely individual roll calls. Under the main Roll Calls entry you will find All River Cruise Roll Calls as the second item. Within that you can search for River Countess, or for the name of the cruise, or you might want to look by the river you will be on, since a lot of the information will be the same whatever line you are on. Enjoy!