Most likely, your system is already installed with audio drivers and the configuration was done at installation time. Likewise, should you ever need to replace your audio hardware, most systems provide tools that allow easy setup and configuration of the device. Most currently available plug-and-play sound cards should be recognized automatically. If you can hear the samples that are played during configuration, just click and everything will be set up for you.
If your card is not detected automatically, you may be presented with a list of sound cards and/or of sound card properties from which to choose. After that, you will have to provide the correct I/O port, IRQ and DMA settings. Information about these settings can be found in your sound card documentation. If you are on a dual boot system with MS Windows, this information can be found in the Windows Control Panel as well.
If your soundcard is not supported by default, you will need to apply other techniques. These are described in the Linux Sound HOWTO.
There are generally two types of sound architecture: the older Open Sound System or OSS, which works with every UNIX-like system, and the newer Advanced Linux Sound Architecture or ALSA, that has better support for Linux, as the name indicates. ALSA also has more features and allows for faster driver development. We will focus here on the ALSA system.
Today, almost all mainstream audio chipsets are supported. Only some high-end professional solutions and some cards developed by manufacturers refusing to document their chipset specifications are unsupported. An overview of supported devices can be found on the ALSA site at http://www.alsa-project.org/alsa-doc/index.php?vendor=All#matrix.
Configuring systems installed with ALSA is done using the alsaconf tool. Additionally, distributions usually provide their own tools for configuring the sound card; these tools might even integrate the old and the new way of handling sound devices.