I'm running Linux Fedora core 7 on my server, just for reference.
For editing/adding/removing the tables/rows/databases in SQL, I use PHPMyAdmin.
See section 2 of this How-To for PHPMyAdmin installation:
http://www.howtoforge.com/virtual_hosti ... ql_fedora7
This how-to is designed for - as the name states - Virtual Hosting with Proftp and MySQL.
But you can use the phpmyadmin simply to administrate mysql, regardless of what you're using mysql for.
And I use a custom-made little PHP thingy to add/edit/disable users.
I'll give the source to you if you like, I don't mind sharing my stuff.
However, RADIUS comes with a nifty web-based application called Dialup_Admin.
for more information.
(My custom PHP thingy doesn't have a Remove User option, dialup-admin does.)
I recommend looking into dialup-admin to administrate your Groups.
(i.e. the IP-pools and it's parameters) I use 10 separate IP Pools, works great.
Just a note - When installing FreeRADIUS - do it using YUM Install.
Compiling it from source will work fine, but it's a MAJOR mission getting it running.
I spent 4 days trying - and failed. Then turned to YUM, and got it running in a few hours.
Save yourself the heart- and headache, use YUM.
If you need more help, just yell.
P.S. Before you go overboard with this option, check out User Manager as well. I'm just not mentioning it because I know nothing about it. But it seems to be highly praised.
Best of luck.