looking for map builder for counter strike source

[GLOBAL_OVERRIDE]

wondering if anyone can help me im looking for tools so i can build custom maps for css:sniper:

 

[diluted]

Download Source SDK in Steam. It comes with a program called Hammer, which is the map editor.

 

[Przemek]

You should also add this website to your bookmarks:
http://developer.valvesoftware.com/wiki/SDK_Docs
It contains a lot of information about Source SDK, including map creation tutorials and links to other websites containing more advanced tutorials