The Nazis wanted the fertile lands in Eastern Europe and Russia for their own supposedly superior people. In fact, one of their most popular slogans was about "Lebensraum im Osten"("space to live in the East"), which, now that I think about it, has a similarity in sound to the slogan of "Manifest Destiny" in the US.
The first step of the "Lebensraum im Osten" plan was to invade Poland. Hitler split it with the Soviets in order to keep the Eastern border calm, since he needed all his forces on the Western front, to handle the backlash by the UK and France over the invasion of Poland. His original plan was to take on the Soviet Union only after having won the war on the Western front.
However, he backtracked on that strategy and invaded the Soviets in 1942 because the war in the West took longer than expected. Several key campaigns on the Eastern front, including the infamous Battle for Stalingrad, were specifically about securing resources like steel and oil (and, conversely, cutting off the Soviets from those supplies).
Disclaimer: I'm not a historian. All this is going off of what I would consider common knowledge as a German.
The biggest wars the US fought are WWII, WWI, and the Civ
In other threads, I've been decrying the degradation in History education in the US and across the western world. It's gotten so that the current generations in the work force only have a "Flintstones" understanding of how the current world got to where it is now, and what lessons can be learned from history.
The biggest wars the US fought are WWII, WWI, and the Civil War. None were over resources.