eat like a fat kid...

if you dont want to do the weight gainer thing... eat 9 big meals a day... try to get 500 calories per meal at least... eat as much as you can... the advantage naturally skinny people have is that they can eat slightly dirtier and benefit from it... what i mean is that you can eat really high g.i. carbs postworkout (g.i.=glycemic index) which will cause you to be very anabolic....

eat like a fat kid and lift very heavy and hard for about 45 mins to an ahour 4 to 5 days a week...