Show/download file from a non public folder

Hi,

I have files(.jpg, .pdf, .rtf, .xls) in the following non-public folder:

/home/alex/documents/

I need to show these files (jpg), or allow the download (.pdf, .rtf ...) fro
m a script for users who already are authenticated and have a session opened
 in the server (this part is already working).

that I can do?

thanks in advance, 

Alex