Selector is a "path" to the specific element you want to collect, you posted the selector to the "FirstName" field.
It is very basic and seems right to me.
What we need to remember of is that each element sits in a "parent window" that has it's own selector.
It is "box in a box" kind of situation": give em "first name" that exists in "window".
So let's see the selector of parent window, can you double click here and post?
I'm pretty sure we need to modify this to make it general, not URL specific:
