How to install steam in ubuntu includes few editing for 32bit and 64bit
1. enable the “multiverse” repository
2. run sudo apt-get update
3. Install steam using either apt-get or the Software Center.
1.add the following line to /etc/apt/sources.list:
deb http://repo.steampowered.com/steam/ precise steam
You must know How to edit the system file in Ubuntu as root?
2. run sudo apt-get update && sudo apt-get install steam-launcher