.htaccess and user file/folder access outside public_html

Hi,

i'm facing a problem and i don't know where to start and in fact, how to 
do it.

Situation:
Users of my website should be able to save their resume files + cover 
letters on my webserver.

problem:
how to make their file SECURED from any hack ? I mean only file owner 
and web administrator (so in this case... myself) should have access to 
those files.
never user B should be able to access, read or download files of user A.

my guess:
i was thinking to store files outside public_html folder, in the 
following way:

/resumes/user A/resume A
/resumes/user A/cover letter A

/resumes/user B/resume B - US
/resumes/user B/resume B - ES
/resumes/user B/cover letter B

Questions:
1. how can i allow user to have access to folder/files outside public_html ?
2. how can i secure that user A has access to his own files ONLY ?

i searched on internet for some help but i did not find anything really 
revelent...only theory and no really in details.

I need your help.
thx.