Why is the "Two way" feature of Vista's Firewall such a secret?

I am totally unable to find out how to enable this feature, though I'm told
that it exists.
I'm running Vista Ultimate.
I've attempted to follow an article in PC Advisor (issue 165) and fell at
the first hurdle!
Quote from Mag :-
Click the start button and in the search field, type "wf.msc".<<

I've heard tell of this "Search Field", but it does not appear when I click
my start button. Using the "Search" > "For files and folders" method which is
the only "search" I can find doesn't recognise the entry "wf.msc".
No where in the "Help" files can I find reference to enabling it, only some
guidance which assumes that you already have it enabled.
Help!!....Please!

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