Gaining Weight 138+?

I'm 5'9 and weight 139 pounds, I barely meet the bmi caluclator for normal. How can I at least gain 15 pounds still with a non fat looking body?
Answer:
To gain weight you have to eat more calories than you burn. When adding calories, try to stay away from adding too much fat. While you can get fat from eating carbohydrates or protein, your body likes to use carbohydrates as fuel more than fat. To gain muscle, in addition to eating more you have to stimulate your muscles enough through resistance training that while they recover, they'll get bigger and stronger. To get an efficient workout you might want to join a gym if you aren't already a member. Guide to Gaining Weight - http://straighthealth.com/pages/guides/g...

---