well, the basic thing you need is a username to login through FTP on your server
how-to FTP server
and probably you don't want to allow that user to have a shell access, so you would add a user like:
Code:
#useradd -s /sbin/false -d /path/to/home-directory/username username
YES, "username" twice (2 times),
this will create a local user on your server with "username" and a "home" directory "/path/to/home-directory/username", but without shell login permissions (-s /sbin/false)
Then you edit the "/etc/passwd" file:
Code:
#vim /etc/passwd
and edit the line with "username::path/to/home-directory" <-- change to /path/to/web/directory (where the web site files are)
then you will need to "chown" that directory and allow others (apache, etc...) to read from it
Code:
#chown username.group /path/to/web/directory -vR
#chmod 755 /path/to/web/directory
this gives the "username" ownership to "path/to/web/directory" and you basically let others to read/execute it (and the files inside).
Now you have to set the password for "username"
Code:
#password username
...enter the password
...repeat the password
Now if you have vsFTPd configured to allow local users to login you will be able to login and upload/change/delete files.
PS. It's a basic FTP configuration, but I see you are using Debian Squeeze which I don't know and I wrote all this for RHEL/Fedora systems
Anyway, good luck