Hey jayson so you want to get bigger... You dont want to be a bodybuilder! i wouldn;t worry about being a bodybuilder becuase theres no chance you will get that bid for a long time. I would suggest the waterbury method for your weight training it calls for heavy weight for the first exercise 10 sets of 3 reps and 4 sets of 6 reps for the rest but you can look that up. Your trying to get bigger and at 5'9" 126 pounds id say you must not be all that strong so youll need to work on that i suggest doing exercises like squats, deadlifts, benchpress, military press, rows, chin ups, dips ect.. youll see them in the waterbury method. you will want to train 3 times a week i would suggest with 4 times being max if your doing an upper and lower body split.
** the number on thing you need to get in order is DIET!!! you wont get bid if your not getting the right amount of nutrients. you should eat 6-10 meals a day if your trying to bulk and you will want at least 1 g of protein per pound of bodyweight. meals should be in certain order.
meal 1 oatmeal and fruit and maybe 1/2 scoop portein, and water
meal 2 veggie, protein, fruit
meal 3 veggie protein -meal10
you will want protein and veggies with almost every meal and make sure to get your whole grains as well as they hold alot of important carbs for bulking.
read the read before posting in the diet area and the waterbury method by chad waterbury and repost a diet and plan and ill take a look
best of luck man