http://www.dota2.com/thebetaisover

Q: If the game is released, why can't I play it right away?

A: We want to avoid a situation where a rush of players overloads our server infrastructure. As we increase our capacity, we will let more people in from the launch queue.

but with this one, you don't have to worry about it.

all you have to do is just carry the folder that you downloaded to steam folder, where it is located, and run the application enclosed.

Have fun!