dont worry! just until few hours ago i think i was just like you
i've been solving the all paper 6 past papers and i still didnt understand some of the stuff so well
even from checking through the mark schemes i still had some doubts
and so i decided to read through my book
and guess wot~ i understand everything now, lolz
it's like magic! lolz, just kidding (soz, i over exaggerated, lolz)
i'm not saying that solving the past papers dont help
they do help, A LOT! but first you've got to understand the terms and then solve the questions
and then you can even predict wot they're gonna ask and everything'll be really easy