Heres a quick list I would lay out for ya
1) Don't look into any pro hormone/steroidal supplements for quite some time.
2) Don't look into commercial weight gainers because there crap. Make your own out of protein, egg whites, peanut butter, fruit, milk, and so on (theres recipes on here)
3) Don't look into any supplements at this moment.
4) Realize that 40-60 lbs will take you anywhere from 2-5 years depending on how much effort you put into this.
5) This intial step in this process does not lie in supplements it will lie in your ability to train hard and more importantly eat quality foods and a lot of it.
Setup a nutritional plan (you don't even have to go overboard and break down every macro in it, but make sure you hit a certain amount of calories a day around a certain macro break down.) I would recommend setting up a daily intake of food so you don't slack but I understand that it can be difficult.
As far as training look into Bill Star's 5x5 program, max ot, and similar programs (or even look at the training logs to formulate a program that suites you.)
Bare Bone Recap: Forget the supplements for the time being because you will be wasting your time/money (this does not include protein powder, EFAs, and multi vitamins.) Find a lifting schedule/program that interests you and you find results from, then give your body the chance to grow (aka get the results you want) but giving it what it needs: rich healthy nutrients from a substantial amount of food.
Again if you really make an effort to eat correctly you will see the results you want (90% of this is nutrition not lifting.) You may find this to be a redundant post, but believe me its the truth.
Best of Luck