MAC OSx file locations/directories

Trying to learn the Mac OSx directory system and where files get stored. Currently a purchased MacBook Pro which "died" after a few days. My data is on it (logged into icloud and some sensitive files) and I cannot log back in. Bootcamp reloading the OS will not finish and I'm having all sorts of issues trying to get back in to wipe the data. I'm going to send this back for a refund but need my data off it. I currently have it setup in my Windows laptop as a slave drive and I can access the harddrive using MacDrive 10. But I don't know where such data would be stored. Any help is appreciated (my last resort it to wipe the drive and just send it back without an OS in it).