Navigation is ran automatically in Tiago, but for running tasks with navigation states you need at least to import the goals to the param server:

roslaunch navigation_mbot nav_common.launch

Inside this launch file nav_common.launch you can also change which file you are importing the goals from. To add more waypoints you can edit the navigation_goals.yaml file chosen. These files are usually under isr_tiago/navigation/maps/<your_map>/navigation_goals.yaml

To run a more personalized navigation please launch

roslaunch navigation_mbot 2dnav.launch