What you think?

Hi MH
I am a young man(19 yrs) , and a thin one.
I know that you posted that the too thin person should not do exercise to gain weight but... I was thinking...
I have to gain 24 Ibs to be in the "right" weight with my height.
So I do not think I am "too" thin and so I was thinking in exercise 3 times in the week, in my home, only with "small" weights to use, between 20 and 60 Ibs.
I am asking this only because I know that you know a lot about health and I can not fast because that will be very bad for me now, since I am thin and I am not independant...
If the time let, I will fast later in my life...
What you think that I can do to get a end in my weight problem right now? And can I exercise???