TurtleBot3 just uses ROS, so if you're not familiar with ROS you can look at some "getting started" content on MATLAB and ROS.
First, you want to bring up all the ROS nodes on the TurtleBot3 itself: http://emanual.robotis.com/docs/en/platform/turtlebot3/bringup/#bringup
Then, you can look at the MATLAB documentation: https://www.mathworks.com/help/robotics/examples/get-started-with-ros.html
Once you've gone over the basics of connecting to your robot, discovering topics, etc., I'd check out this guide, videos, and examples from my team's blog: https://blogs.mathworks.com/racing-lounge/2017/11/08/matlab-simulink-ros/
We also just released a new post showing some TurtleBot3 AutoRace simulation examples with camera and lidar! https://blogs.mathworks.com/racing-lounge/2018/09/12/autonomous-systems-sensors/
- Sebastian
