Make sure you have all courses selected to display (Map Settings/Plotted Courses/All). You may want to pause the game at this point "SPACE BAR".

You will note that the missions are taking off and plotting an AI derived course. This is a pretty basic course as the range of these aircraft is limited, but you can change it if you wish.

Select a unit, its course will appear brighter than the rest. Each course will generally have 5 nodes, a mid-course ingress and egress, an IP (Initial Point where it starts its attack run), the Target which it may not reach if munitions are expended first, and where it enters the final approach for the base. Flight plan modification is covered in more depth in the Multi-Domain Strike Planner Tutorials.

You may also note that the order may not be perfect, perhaps not enough time was allowed to unscramble the traffic at the base. Once again, experimentation is good, perhaps after the first strike it doesn't matter.