How did nazi germany finance itself during ww2?

The Nazis confiscated the money and possession of the people it conquered, and it also confiscated the possessions of its own Jewish citizens : this contributed greatly to their wealth. 

Before the war they motivated the whole country to work for the country: so people worked a lot rather than focused on their private life - this means that the unemployment was low but also the cost of work was not too high. They also invested a lot into the infrastructure with borrowed money (budget deficit).