How and why did the Treaty of Versailles not provide France with long-lasting security?
The Treaty of Versailles did not provide France with long-lasting security because its provisions both A) made Germany very upset and hungry for revenge and B) were not easy to enforce unless the Allies were willing to commit to war.
The Treaty of Versailles included many provisions meant to make Germany weak. These were things like severe limitations on their armed forces and the war reparations they were forced to pay. These provisions made Germans very bitter and eager to get revenge.
At the same time, the treaty did not really guarantee that many of the provisions could or would be enforced. There was no way to stop Germany from rearming or from putting troops back into the Rhineland. The only way to stop them was to fight and France and England were not willing to do that in the time between WWI and WWII.
The Treaty of Versailles, then, was harsh enough to make Germany want revenge but too weak to keep Germany from regaining power. This was a very bad combination.