Just drag the "tfc" folder that was unzipped, into you Half-Life directory.  
This will put all files in there correct places.  None of the existing 
files in your TFC directory will be overwritten unless they have the same 
name as a files in my folder (This is unlikely since all of my files have 
are named quadgod.xxx with the exception of Quadme!.txt).

If you unzipped the file in your half-life directory you're already set.

BE SURE TO READ THE TEXT FILE * QuadMe!.txt * for instructions and copyright 
info.  It will be in a new folder in your Half-Life\TFC\Maps directory.  
The folder is called "TextFiles".  I suggest putting all text files from 
user maps here.  The exception is .txt files with the same name as the bsp 
it came with.  These files are displayed when a map is started, it is what 
gives the brief description of the map before you play it.  Those files 
must stay in the "maps" directory to work correctly.

Remember, read the QuadMe!.txt to learn the nuances of the map or your 
enemies may learn them first.  

enjoy,

Rize