So,i am playing with japan.I thought it would be a good ideea to conquer some cities.So i decide to atack spain.I try to go to the diplomacy screen and declare war on spain,but isabella doesn`t want to speak to me(i broke my relations with her at the request of the russians).So i do not know how to declare war and hot to attack their units.My friend says that when i order a unit to go in a square inhabited by another unit,i will be asked if i want to attack the unit or no.That doesnt happen.
So,how do i atack?

As long as you don't have open borders with them, just moving into their territory will start a war. (Nice change over Civ3... best one yet, followed only by being able to stack in the same square as foreign units.)

ALT + click on name at bottom right corner.