To create a map using Turtlebot3 and SLAM, follow the steps demonstrated in the links below:
https://emanual.robotis.com/docs/en/platform/turtlebot3/quick-start/#pc-setup
https://emanual.robotis.com/docs/en/platform/turtlebot3/simulation/#gazebo-simulation
https://emanual.robotis.com/docs/en/platform/turtlebot3/slam_simulation/