How to change the name of my Garry's Mod Server

Go to your control panel and login http://gp.nitrous-networks.co.uk/
Once logged in, go to your Garry's Mod server and into configuration files, then click the text editor link to the right of the server.cfg file
In this file, change the hostname value to whatever you want, for example "Super Awesome Sandbox" (The hostname must be in between the speech marks)