How To Install Maps

We'll start with Counter-Strike:Source (CS:S)

Download the map and open the .zip or .rar file

Most mappers will zip up the map with all the proper directory structure, if they do you can
easily transfer the zip files to your cstrike folders. But for those who need more help...
*Also on a special note, some mappers put their custom files in a folder named after their map,
in this case you would put the their whole folder into the proper directory*

Next Browse to the Steam folder on your harddrive, now browse to the following directories:

Maps Folder

mapname.bsp , mapname.txt , mapname.nav , mapname.res (these are used mainly for servers)
go to C:\Program Files\Steam\SteamApps\username\counter-strike source\cstrike\maps

Now there also could be a graph folder inside the maps folder you downloaded

mapname.ain files
go to C:\Program Files\Steam\SteamApps\username\counter-strike source\cstrike\maps\graphs

mapname.cache files
go to C:\Program Files\Steam\SteamApps\username\counter-strike source\cstrike\maps\soundcache

Materials Folder

.VMT & .VMF
go to C:\Program Files\Steam\SteamApps\username\counter-strike source\cstrike\materials

This is where most of the mappers make their own folders. Place the whole folder into
the materials folder. example below:
if I downloaded the map the map de_quebec which comes with a custom folder name, I would
place the whole folder into the materials folder
C:\Program Files\Steam\SteamApps\username\counter-strike source\cstrike\materials\de_quebec

Models Folder

.mdl files
go to C:\Program Files\Steam\SteamApps\username\counter-strike source\cstrike\models

Sound Folder

.WAV files
go to C:\Program Files\Steam\SteamApps\username\counter-strike source\cstrike\sound

Now for Counter-Strike 1.6 (CS 1.6)

Basically the same thing as above, except for the main directory.

Maps Folder

mapname.bsp , mapname.txt , mapname.res(these are used mainly for servers)
go to C:\Program Files\Steam\SteamApps\username\counter-strike\cstrike\maps

GFX Folder (custom Skies)

These can be either skyname.tga or skyname.bmp (6 of either one)
go to C:\Program Files\Steam\SteamApps\username\counter-strike\cstrike\gfx\env

Models Folder

.mdl files
go to C:\Program Files\Steam\SteamApps\username\counter-strike\cstrike\models

Sound Folder

.wav files
go to C:\Program Files\Steam\SteamApps\username\counter-strike\cstrike\sound

Sprites Folder

.spr files
go to C:\Program Files\Steam\SteamApps\username\counter-strike\cstrike\sprites

Custom Textures (wads)

.wad files
go to C:\Program Files\Steam\SteamApps\username\counter-strike\cstrike

Overviews

mapname.bmp or mapname.tga and there will be a little mapname.text file with it
go to C:\Program Files\Steam\SteamApps\username\counter-strike\cstrike\overviews