If your main goal is to add muscle, peptides aren't really going to help you.
First thing you need to do is do a consistent amount of resistance training, and upto a weight that fatigues you, not just going through the motions of lifting stupid light weights with no struggle.
Next thing is to eat 0.75-1g of protein for every pound of bodyweight you are.
The above 2 are the basics, not optional.
Next up you you could look at testosterone, creatine.
Finally, for people wanting to be bodybuilders or elite athletes, you'd be looking Anabolics and HGH.