Oki, I think that it came with HalfLife installation of 1.6, but it still doesn't work. It shows me this:
No detail texture mapping file: maps/esf_cellgames_detail.txt
Couldn't exec banned.cfg
Lan servers are restricted to local clients (class C)
It means that the Server you are attempting to play on is LAN only. Which means only computers connected to his LAN Network can join the server only. But i have a feeling you are using the WON version, and not STEAM. Download Steam, and try again.