Accessing files via FTP in PHP

Hi, I have main account which contains the upload script files There are many logic's in this script like listing files, checking size and uploading files etc.. From the main account /home/mainuser/public_html/(the script goes here) The log in users should use the script to access their files from their account Example User1 will use the script here /home/mainuser/public_html/(the script goes here) To access his/her files here /home/user1/public_html/(files) Please note each user has one FTP account in place. I need to modify the script to add this file accessing functionality.