I have a history assignment, the question that I have to answer in detail, is 'The Assassination of Franz Ferdinand was the most important reason why World War 1 broke out? To what extent do you agree/disagree with this statement?"
So, if I understand this correctly, your teacher has given you an outline (bottom part of the picture) of exactly how they want you to do this essay, is that correct? If so, all you really have to do is to follow that outline.
You need to start with an introduction. It looks like your teacher has told you what to say. You need to start by saying that the great powers went to war in 1914 and that the outbreak of war was caused by the assassination. Then, you are supposed to say that your essay will prove that there were many factors that helped cause the war. I would expect you to say in your introduction whether you believe that the assassination was the main cause or just a small factor (or somewhere in between). Your teacher does not say to do this, though, so I do not know if he or she does not want to see that.
Then you are supposed to devote two body paragraphs to arguing that the assassination was the most important reason for the war. Your first paragraph is supposed to say that the assassination caused the system of alliances to come into effect. You should discuss the two main alliances (Triple Accord and Triple Entente). You should then say that, because of the assassination, they came into effect. When Austria declared war on Serbia, Russia was obligated to enter the war. When Russia entered, Germany was obliged to defend Austria, and so on. Your next paragraph is supposed to say that nationalism caused the assassination to happen. You would need to define nationalism. You would need to point out that the Archduke was an ethnic German and that his empire ruled many people who were Slavs. Slavic nationalism led them to want to kill him. This would explain how nationalism led to the assassination.
Next, you are supposed to have two paragraphs in which you disagree with the idea that the assassination was the main cause of the war. The first of these paragraphs is supposed to argue that the war started because Germany felt surrounded. You need to discuss how Germany felt that the alliance between Russia and France was aimed at them and how they felt they needed to fight before that alliance became too powerful. You will need to say that this led to an arms race between Germany and the other countries. This arms race made the various countries even more worried about one another and made war more likely. Your second paragraph needs to bring in other causes of the war. I don’t know what your teacher has talked about, but I would mention Germany’s desire for “a place in the sun.” In other words, Germany wanted to have more power and the other countries wanted to keep it from getting that power because they feared what Germany would do. You could also mention militarism. You could talk about how all the various countries were coming to believe that military force was the way to solve problems. You could talk about how they were glorifying the military and thinking it was superior to civilians. This led to a situation where military leaders could push civilian leaders into approving of war.
You are supposed to end with a conclusion in which you weigh both sides of the argument and decide what your opinion is. Which side of the argument do you agree with?
As far as I can tell, this is what you are supposed to do based on what you have shown us.