Brandireggie, There a several ways of doing the edit, but this is what I would recommend for simplicity:
- Install an ftp client application to the mac or pc I'm using if one is not already installed
- set up a connection to the web space using the connection details supplied by the web host
- connect to the webspace and download the wp-config.php from the WordPress installation to the desktop of my mac or pc
- edit the wp-config.php in a text editor and save it
- upload the edited version to replace the original copy
This is the kind of thing I do very often on the sites I manage, so its easy for me but I understand its not so easy if you have never had to do it before, especially if your site is down.
If this still seems a bit daunting, If you don't have a local techie you can call on, would you like some help?
If send me a msg via my site: http://www.cubecolour.co.uk/contact/, I'll be happy to do the edit for you (I will need your ftp connection details)
Ipstenu is correct that you will should really be comfortable with this process to solve issues when self-hosting any web application.
if you do give it a go yourself, hopefully you'll find its not as difficult as it first seems as long as you understand each step.
good luck!