Table of Contents
This process depends if you own a physical copy of Quake or if you downloaded it.
Since there were various releases of Quake around this is not as straightforward as you might have hoped. TODO, someone get guides like these into the wiki: http://mhquake.blogspot.com/p/installing-quake-using-dos-box.html & http://icculus.org/twilight/darkplaces/readme.html#HowToInstallQuake_Windows
Follow the instructions.
You should now have Quake installed.
Let's call the directory where Quake is installed the "Quake directory" from now on. So for example your Quake directory is "C:\Quake\" or "/home/ranger/ games/quake/". If you do not know where it is, try searching for a file called pak0.pak. It should be inside a directory called id1 which itself is inside your Quake directory.
Inside the Quake directory there might be some files, these will not be needed. However there must be a directory "id1" and inside that directory must be at least a file called pak0.pak and if you own the full version of Quake also a file called pak1.pak.
|pak0.pak||17M (that is 18689235 bytes)||5906e5998fc3d896ddaf5e6a62e03abb|
|pak1.pak||33M (that is 34257856 bytes)||d76b3e5678f0b64ac74ce5e340e6a685|
Is that the case? Excellent! If not, go find the pak0.pak and pak1.pak files on your media and create a file structure like that. If you cannot find them, start from the beginning or ask in the forum.
If you want to learn a bit about the directory and file structure of Quake then read on. If not, skip to the next step: Quake Configuration
The file/directory structure
A raw Quake installation consists of two elements: The executable (we call it engine) and the game data. The executable (usually) expects the game data to be in a directory on the same level as itself. In the case of the original game you need to have some .exe file in your Quake directory and a directory called id1. This is the game directory. Inside the id1 directory there are the .pak files. These contain the game data (levels, sounds, models, etc.). Think of them as archives, like ZIP but uncompressed).
By default Quake tries to load game data from the id1 directory when it launches.
Some mods do not bother with putting their data into pak files, they instead dump all their files straight into their game directory.