jackal gazebo simulation question

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After I going through the tutorials offered by Clearpath, I can run the demo offered by the tutorial and navigate the jackal robot around the map using the 2D navigation icon. Also I can use rqt to check the state of the jackal robot while it's moving.

Now I want to set some goal points in the map and let the robot go through each goal point one at a time until it gets the final goal point with my own control algorithm.

Any inspiration about how I can finish this task? Also I can find any topic in the demo related to the global coordinate of the robot. How can I set some goal points with respect to some global frame?