Structure Type Var from a Variable?

I am trying to record results of a game, to basically know in which I am trying to get the question right.
Now I am using a variable type structure, but I don’t know how I can assign a value to this structure referring to a variable that I have already defined?
This is how i define a Var:

And this is how i define the Structure

As explained on the wiki, you need to use the brackets notation to access a variable dxnamically. In your case, result[Variable(pos)].key.