For a traditional serving of matcha, you typically use  2 grams of ceremonial matcha powder. This is roughly equivalent to 1 teaspoon. If you're preparing matcha using a bamboo whisk (chasen), you would usually sift the powder into a bowl, add about 70-100 mlof hot water (not boiling, ideally around 80°C), and whisk until frothy.
If you prefer a stronger or weaker taste, you can adjust the amount of matcha to suit your taste.