You can see The Nile River Basin (Green) and a city. The starting city is in the north when you got the city correct a new city will appear towards south and so on. Good Luck!
You can always move on to the next city by using the up and down arrow!
It's a good thing you mentioned that you can skip to the next city with the down arrow. I couldn't get the first one and thought I was going to finish with 0!