French language Q&A Forum

I found this very difficult and frustrating.  Some of the words I thought I needed were not in my dictionary or were very different from what I expected:  Silicon was translated to be silicium (!); liposuction was nowhere to be found.  I don't recall having see the expression "couter les yeux et la tete" before (although there is some faint recollection of it).  Poser, used I think in its possible form,  is to install, but not a term I would have associated with breast implants.  I think I need MUCH more information and education in current terminology to feel any success with this translations.  How do I get this?????  Help, please!!

Elles ne connaitront jamais mon secret is the given answer. Why will savoir in the future not do? Various dictionaries suggest they are equivalent for this kind of statement.

dont was whose earlier but know means of whom/which. i'm getting muddled even thogh ive just gone through lessons again. Can some one make it a little simpler please. Or just a different explaination