Personally, I use MUSHclient. You can find it from

http://www.gammon.com.au/downloads/dlmushclient.htm

The client is actually not free, but you can use the free shareware version indefinitely. The shareware version has a nag screen when it opens, but otherwise it works just as well as registered version(I use the shareware version too). After you've installed the client, choose 'new world' and add Carrion Fields. The MUD adress is www.carrionfields.com and port is 9999. After you've added Carrion Fields, all you need to do is to load the world with your client in order to start playing. It is possible to play using telnet too(the connect button on the page opens your default telnet client and tries to connect to CF), but I prefer having a client.