Typically, you would place the .cfg file into your CS 1.6 valve or cstrike directory, often located at C:\Program Files (x86)\Steam\steamapps\common\Half-Life\valve or a similar path, depending on your installation.

: Approximately 39% of CS 1.6 servers are reported as malicious and may attempt to exploit client flaws.

Using third-party "free" wallhack configurations or software carries significant risks for your account and your computer's security: Valve Anti-Cheat (VAC) System - Steam Support

Historically, players sought "Asus Wallhacks" or specific driver manipulations that forced the game to render textures as transparent. OpenGL Scripts:

The Myth and Reality of the "CS 1.6 Wallhack CFG": Can a Config Truly Give You X-Ray Vision?