Proftpd + Apache: a question on ftp access configuration

I installed a small web server on Slackware 9.1.0 for SNMP/MRTG purposes.

I created a virtual web server on: /var/www/virtual/mrtg/htdocs/

Everything is fine.

Now I want to create FTP access for a UID called "mrtg", so that a web
designer will be able to modify the MRTG web pages contained in
/var/www/virtual//mrtg/htdocs/

I did: useradd -g users -G ftp -d /var/www/virtual/mrtg/htdocs/ -s /bin/bash
mrtg

and I created a password

It works, but only in read mode. Actually:

root@sarune:~# ls -l /var/www/virtual/mrtg/
total 6
drwxr-xr-x 2 root root 5448 Dec 18 13:20 htdocs/

What should I do now? A "chmod o+w /var/www/virtual/mrtg/htdocs" ?

Are there security issues? Is there a better way to configure it?

The reason why I am asking this, is that it's the first time that I am
exploring an Apache + FTP configuration...

Thanks for your help and/or hints