Total Newbie

[sb2013]

alrighty so down to business. im 22, 5'6 so im a short shit, can pack on muscle pretty quickly when i try, and at the moment i have a terrible lifestyle. I eat tonnes of junk food, i smoke heaps and i don't exercise (apart from what i get at work) so i am mega out of shape. 12 months ago i was twig thin (almost anorexic) from my amazing diet of energy drinks, alcohol and no solid food (i worked far too much to have time to eat) anyway i have always wanted to be 'bigger' coz im a small guy. in the last 12 months i have packed on probably 20kg solely on my belly and arse region. now im happy with it but i want it to be more solid and defined not jiggly. essentially i want to get to that muscle chub/cub stage, you know the ones with arms bigger than my legs and necks as wide as my torso and i have not the faintest clue where to start or what to do. i used to work as an abbatoir worker and lifting heavy dead animals around all day made my upper half and arms bulk out massively, only problem was i was twig thin because i was working 16 hr days and yet again eating like shit. anyway any help would be appreciated fellas.