You have downloaded maps for the Counterstrke-BETA program.
As one of Valve's promises of delivering the SDK for HL2 months ago has been delayed or possibly canceled,
an alternative measure has been taken for the outcome of this release.

Just extract the cstrike folder with all the files to 

Valve\Steam\SteamApps\YOUR EMAIL OR USERNAME FOLDER\counter-strike source beta\


Greetz, Have Fun !!!