On http://www.minecraft.net you sing in (upper left corner), click on In browser or Download on "Minecraft Alpha [The latest!]: In browser | Download". The rest should be findable on your own, as should have been the above (unless you're visually or otherwise impaired, in which cases I forgive you for not looking...)
REALLY, open your eyes and look, that's what evolution "made" them for!
Also, DO NOT BUMP, even if your thread is MORE THAN 9000 msecs old