The main Resources are produced at the Resource Production Buildings inside your Base: Drop Zones, Munitions Factories, and Wellheads. To produce more Resources, upgrade these Buildings and other Resource related Buildings such as the Refinery and the Munitions Fabricator. Please note that the Control Tower does not increase Ration Production, but instead reduces Ration Consumption.
Some Resource Production Buildings are locked at the beginning of the game, and can only be upgraded upon reaching a certain Level.