Which OS are you using, "frambuesa", "escarlata"?
If you connect the ethernet wire to your Erle-Brain 2 he get internet connection automatically.
If you're using "frambuesa" OS (this is the recommended version), you need download the necessary debian package, here an example for a quadcopter:
sudo apt-get update
sudo apt-get install apm-copter-erlebrain
If you're using "escarlata" OS, connect your Erle-Brain 2 to a monitor using HDMI and choose the robot in the pop up message.