More information is available for system administrators in the System Administrators Guide.
You will need two tools: a text editor, in order to edit text files, and a FTP client, in order to transfer files from your machine to your server.
Here are a few well-known text editors:
Note: do NOT use a word processor, such as Microsoft Word or OpenOffice.org Write when editing text files.
FTP is short for "File Transfer Protocol", meaning the standard way used to transfer files from a computer to a web-host.