From Livestream » User Guide
How do I stream video games?
1. To begin, download Procaster and install it onto your Windows-based system. We recommend running Procaster with Windows 7, Vista, or XP.
2. Log in with your Livestream Username and Password. Select your channel and edit your settings.
3. Start your video game. You'll see a Green Livestream Logo on the top left of the screen (or wherever configured). Press Ctrl + F1 (or configured hotkey) to begin broadcasting from within your game. The logo should then change to Red. This indicates that you are streaming.