Since giving up smoking I've been trying to do the same thing & in the 4 months thatI've given up I've put on 2 stone which is something I really needed to do & I've still got another stone that I want to put on.
I've been searching through loads of websites etc trying to find diets & routines that will help me gain weight. So I normally eat 4 times a day which is breakfast, a snack around 10 ish, lunch & dinner & a supplement drink just before bed (Pro Lab NLarge 2) & I may sometimes have this with breakfast as well. & I'm also training 4 times a week as well.
The below website I found really useful as it gives sample diets & workout routines etc which I've found really helped me
http://www.gain-weight-muscle-fast.c...diet-plan.html
Hopefully some of the above can be of some use & I'm not just waffling