Help - I'm new and need help in installing downloads.

I've bought the WINRAR program and had it registered.
I've also tried to follow the instructions in the 'Knowledge Center'.
But due to my lack of experience (and most likely inaptitude+) I am unable
to install the airlines into FSX. I cannot find files, folders etc etc.
In the past, I used Addit! Pro. Yet, it seems that the site is 'out'
and there's no reply to any inquiries or e-mails. 
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Could anyone help.
Thank you,
Pinny.