U.S. government's role during World War II in mobilizing the economy for war: The following paragraph is lifted off of page 468 of American Military History from Center of Military History, United States Army, about 1988.
"An imposing structure of federal agencies and committees grew up in Washington to control the nation's economic mobilization. Its keystone was the influential War Production Board (WPB) that controlled the allocation and the use of raw materials, machine tools, and facilities, with powers similar to those of the War Industries Board in World War I. In the military spnere the War Department, like the Navy Department, had a large degree of autonomy in controlling requirements planning, production, and distribution of material for its forces. The actual procurement--that is, purchasing and contracting of munitions and other war materials--was carried out directly by the Army's technical services and the Navy's bureaus. Within the Joint Chiefs of Staff organization many logistical problems at issue between the services were settled by negotiation. The War Shipping Administration (WSA) operated and allocated the critical United States merchant shipping. Close co-operation between WSA and the British Ministry of War Transport resulted in the pooling of the two merchant fleets, comprising the bulk of the world's mercantile tonnage. Other civilian agencies dealt with such critical commodities as food, petroleum products, and rubber. In the spring of 1943 most of the mobilization agencies were subordinated to a new co-ordinating unit, the Office of War Mobilitation headed by former Justice James F. Byrnes."
I am pretty sure that your text will have some particular answer you are expected to give because this is a pretty broad question.
In general, the federal government did everything to gear the economy up for wartime production. They, of course, were the ones who ordered all the weapons and things that the military was going to need. They were the ones who set up the rationing schemes that were going to be needed to make sure that there were enough supplies.
So no one else was really involved in gearing the economy up for war.
The federal government allocated money to increase the size of the military. Some of these funds came from money gained when America sold munitions and other supplies to France, Britain, and China under the Neutrality Act of 1939. The federal government also set up various agencies to manage consumer production, inflation and pricing, mobilization, production, and wartime propaganda. The government also promoted big businesses to produce for the war effort by giving loans at low interest rates, subsidies, and tax write-offs.