You should read the game manual.
If you want to increase basic resource production look for buildings that increase resource production (e.g., Railroad, Factory, Harbor). Resource production is also affected by province morale (see chapter 3 'Governing your Country'). Shortages of any resource may lead to morale loss and may even affect units' effectiveness in battle. Production and consumption values change depending on a positive or negative value, which will determine the production of resources. Thus, your resource balance is constantly increasing/decreasing.
