Yes, you add all three parts to your nutrient tank or reservoir one at a time. Usually you add the Micro and stir it in, followed by either the Bloom or Grow, and mix it in well.
All three parts contain different minerals and elements that the plant will use from seedling to full growth bloom. Follow the chart and pick the corresponding week you’re in (i.e. Week 2 of veg) and then add the amounts it suggests, multiplied by the number of litres of water in your reservoir.