How did the Nazis demonstrate support …

 The German's supported Hitler because of the Versaille treaty/agreement that the allies made after WWI. The Germans were forced to pay millions of dollars to compensate the allies and so many of them became poor. Hitler rose up and declared that the Versaille treaty/agreement was unjust (which it was to a degree but it still shouldn't have led to war) and that the Jews were taking all the work that the German people needed (there were a lot of unemployed Germans, however, the Jews had great businesses) so Hitler started the Nazi party and gained more and more influence, and more and more power. At one stage, he usurped the government but was put in prison. He was still popular however and was let out a while later, only to rise to power again and this time receive full command of Germany. The rest is history.