How did the construction of the Berlin Wall help to create Cold War tensions?
Historians argue that the construction of the wall actually did more to reduce Cold War tensions than to raise them. It took the pressure off of the Soviets to do something about the fact that millions of East Germans were escaping to West Berlin. The East German government had been pushing the Russians to take West Berlin from the Western Allies. The wall solved this.
If you have to argue that the wall raised tensions, you can say that it increased Western animosity towards the communists. You can say that it made the West feel even more strongly that communism was an evil system. This made them more likely to resist communist expansion and increased tensions.