How to Install Dota 2 on Steam - Install Dota 2 on your Steam Account
Go to Steam's website (http://store.steampowered.com/) and
download the setup file (1.5MB).
Once the installation is finished, it will update itself,
which takes around 5 minutes or more.unt, you can tick "Don't save account credentials on this computer" as well.
Make a new account if you haven't already (using Steam).
Validate your account through your email as well to protect it.
This secures your account whenever you try logging in from
a different computer.
Library > Add a Game > Activate a Product on Steam.
This will open a dialog box for you to follow.
Enter your Dota 2 beta key.
If it's genuine, then there should be no problem for
Steam to accept it and for you to start the download.
Download Dota 2 via Steam by clicking Install/Update.
Depending on the speed of your internet connection,
it might take anywhere from half an hour to overnight.
An average of 500kbps will download the game in
around 1 hour and 15 minutes.
Update your game.
Regular updates are on every Thursday.
Click Play. If there is an update, it will automatically
receive it before you get to play the game.
Updates are around 200MB or less (for smaller updates),
so it won't take much time.
HOW TO HAVE A PORTABLE DOTA 2?
Note: I assume your Steam folder is inside C:\Program Files\Steam in this tutorial (Windows XP).
If you don't have Dota 2 on your USB or storage device yet, but you already have it on your computer,
copy the folder named "steamapps" inside C:\Program Files\Steam into your USB or storage device.
After installing Steam and Dota 2, copy the stored "steamapps" into C:\Program Files\Steam.
You can do this as Steam is updating itself on your new computer after installation.
You might need to validate your account as you log in if you secured it.
Just copy the five-character code sent to your email address and you're good to go.
After copying, go back to Library > Dota 2 then click Play.
Steam will start checking for updates. If there are none, you're good to go!
Simple as that! No compressing or whatever required!
If you don't want anyone potentially messing up your Steam or Dota 2 account if you're on shared computers, under the "Local Files" tab, you can select "Delete Local Game Content" to remove Dota 2 from the computer. Also, under Steam > Settings > Account, you can tick "Don't save account credentials on this computer" as well.
Remember to update the stored Dota 2 folder in your USB if it there was a new release by overwriting it. This makes sure you don't have to update it again and again when new releases are out.