First Crystal, please don't forget to say please - everyone does so on this forum.Secondly, as for your question:
You need THREE ways that the Treaty of Versailles caused World War II.
OK...
Idea One: how did the Germans feel about the Treaty -- look at
this webpage? How might that have helped Hitler come to power? How might that have caused germany to behave in a way which plunged Europe into war in 1939? If you look at this list of
'steps to WWII', how many of them go back to Hitler trying to reverse
the terms of the ToV?
Idea Two: how did the Allies feel about the Treaty -- look at
this webpage? How might that have affected the statesmen of Europe as they tried to deal with hitler in the 1930s - can you find on
this webpage examples of them giving way to Hitler because they felt that Hitler was actually quite justified?
Idea Three: how did the Treaty of versailles affect the map of eastern Europe -- look at
this webpage to see how it replaced the huge empires of Russia and Austria-Hungary with lots of tiny, weak states. How might that have helped Hitler? If you look at this list of
'steps to WWII', how many of them involve Hitler dominating a small state set up by the ToV?