To become muscular, you will need years of productive exercise and proper diet.
But if you have chosen this path, you are real man. And your authority among girls will be significantly higher than that of ordinary guys who do not develop physically. After all, it's not just a beautiful body, but also that daily restrictions make you stronger and girls see it.
You become stronger not only in body but also in spirit. You will develop confidence, which is very important for every man. So, in order to build a muscular body, you should sign up for a gym and find a suitable trainer who will prescribe a training program for you and will monitor your progress.
Often the trainers themselves can make a diet for you that you have to strictly adhere to.
Don't forget to get enough sleep and give your muscles a break. Sleep at least 8 hours a day. Drink plenty of water and quit bad habits.