The fourth-octave fingerings are available on the following site:
http://www.wfg.woodwind.org/index.html
It also includes trills, tremolos, and alternate fingerings for piccolo (very handy!). Those off-brand flutes frequently suffer from bending

, just because the metal is very soft, not a standard grade used in the US. But your flute at least helped you get started and realize you enjoy playing it, so it wasn't a complete bust, no? Ah,
Southern Harmony! Our All-State band played some movements of this piece a couple years ago, and, not only are there D-flats up there, there's also a D#!!! Of all the pitches above C, this one seems to be least responsive

. I have, literally, 16 fingerings for this note, and ONE of them works on my flute (Muramatsu). My student had second chair, and, despite much effort and everything else sounding pretty good, couldn't make any of the D# fingerings speak. I think, also, Trevor Wye saves the D# for last on the fourth-octave study page, because it's so nasty.