What kind of server? Like one in your house or a server that you would rent from godaddy,. the planet etc?
Well, first you will need to choose a platform: a) Linux In this case you will probably want to use Apache web server. There are plenty of guides on the Web on how to install and configure Apache. In case you want to host more domains on one server, you will need to configure virtual hosts. The most popular scripting language is PHP, other major ones are Python, Ruby etc. You might also need a database such as MySQL, PostgreSQL or SQLite. I recommend installing all at once - google LAMP. b) Windows In this case you will probably use IIS 7. You have range of scripting laguages, most popular on Windows platforms is .NET but you can also use PHP with IIS (in version 5.3 Windows support has been improved rapidly). For database you will probably use MS SQL or MySQL. --------------------------------------------------- Of course, you will need to install and configure FTP server, Mail server etc to be able to use the server properly. You can also install a control panel software that will make it easier to manage the server and websites on it (cPanel, Plesk, DirectAdmin, DotNetPanel etc).
Does this thread even make sense in the HTML/CSS section? There is a Server section in Web Design... maybe this thread would get more life over there? (not that risoknop's answer isn't excellent... though of course I must add Perl to the P in LAMP : )