I'm thinking you'd be best off eating. ALOT. 4k cals a day. at 6ft and 145 eating a metric ton of food is your best option. dont worry about spending money on supps yet. if you're hell bent on taking something, get a mass gainer with creatine OR just plain ol' blended protien (syntha-6 or myofusion are the first that pop into mind because theyre my favorite as far as taste). you dont have to pick those two theyre just examples of a blend of whey, casein, egg, and i think theres a bit more in there. just pick sometihng that fits your budget and you can stomach.