Cesar, Congratulations on taking an interest in your health and in starting your exercise. Your question is not a simple one. Not everyone who starts exercise needs protein powder. That is a misunderstanding that I hope did not originate from previous answers to other queries. The need for protein powder is based on the overall diet and whether the protein can be consumed from foods or not. It depends on whether you are vegetarian, vegan, lifestyle, type of exercise and intensity. To provide a general answer, if protein powder is used to supplement the diet, it can be used in a variety of ways. The most popular way is to put one scoop into some beverage (milk, juice, almond milk, soy milk) and stir it up or if you have a blender, put liquid in blender, add frozen fruit, grind on high, add protein powder, some cinnamon or vanilla. There are books on recipes for protein powder drinks. Protein powder should not contain a host of other additives or claims. Just pure isolated whey (look for isolated, it is 90% protein). No growth factors, nothing else. Amino acids may be listed. It might have stevia in it (a sweetening herb). No growth hormone releasers or other claims. It is more important to replace carbohydrates with the protein, not just protein. And while there is debate as to whether to take the supplement before or after I usually determine that after doing an assessment. If you take it after workout, do it within 30 minutes of workout. Fluids must be replaced. Weigh before and after exercise. For every pound lost drink 3 cups of fluid. I am encouraging you to improve your diet. Your weight seems very low but I do not have your height or age. I suspect you should include nuts and seeds and nut butter in your diet if trying to gain weight. If you need more guidance, please write back. And, I suggest you have a Dietitian review your diet and exercise plan to assist you to develop an optimum plan. Regards, Kathryn Shattler,MS,RDN