EAT-Really check and make sure your eating enough calories(4000-5000)- then if you dont gain weight add 500 calories each week until you gain weight---make sure you include lots of carbs and fat and obviously protein
-----YOU WILL GAIN WEIGHT EVENTUALLY------
DONT DO ANY CARDIO(BASKETBALL,TENNIS,ANYTHING WHERE YOU SWEAT-EXCEPT SEX)
LEARN TO RELAX
Work out heavy- 4-6 reps max
And if you choose to take steroids---but I would try to reach my natural peak first.
Good luck man