How do I start turtlebot_simulator correctly

edit

That doesn't work either, FYI I created and run the setup.sh:

#!/bin/sh
source /opt/ros/electric/setup.bash
export ROS_ROOT=/opt/ros/electric/ros
export PATH=$ROS_ROOT/bin:$PATH
export PYTHONPATH=$ROS_ROOT/core/roslib/src:$PYTHONPATH
export ROS_PACKAGE_PATH=~/ros_workspace:/opt/ros/electric/stacks:$ROS_PACKAGE_PATH

Then installed the extra package:

sudo apt-get install ros-electric-turtlebot-desktop

However I still get the same error when I run the turtlebot simulator via:

roslaunch turtlebot_gazebo turtlebot_empty_world.launch
[turtlebot_gazebo] is not a package or launch file name

Any ideas?

Awesome. Works now.