You're undoubtedly ready to see all this hard work in action. Now you can assemble the final spot with each of the sections. This will take practically no time at all:
Create a new composition named Squares2_Final with dimensions 720x540, Frame Rate 29.97, and Duration 30:00.
At time 0;00, add Section1_Orange to the Timeline.
Go to time 7;00, and add Section2_Green to the Timeline.
Go to time 14;15, and add Section3_Purple to the Timeline.
Go to time 22;00, and add Section4_Yellow to the Timeline.