"Before looking into the box, get permission!"
Translation:Kutunun içine bakmadan önce izin al!
You maybe a tad confused with word meanings... Basically için = for... but adding "de" and "e" and "den" changes its meaning
içinde = in / inside (de = at inside) içine = into (e = to inside) içinden = within (den = from inside)
But there are a few more variations for these depending on the instance or tense of the sentence.