How to instantiate in Hierachy

So how do I instantiate an object at a set position the the Hierarchy? Currently when I instantiate an object using…

directoryButton[x]=Instantiate (firstButtonObject);

…it appears in the root. (even if the original obeject was a child object of another in the Hierarchy pane. I want the object to be a child of another object once created.

Any ideas? I coulnt find anything in the docs.
Cheers

for parenting use transform.parent which would be the transform of the object you want to parent it to…