If you press the Ripple button and move a clip to the left or right the other clips on that same track will follow. If you press the second Ripple button to the right of the first one it will make the clips on tracks above and below follow. So you can use that button to quickly move many clips especially clips on other tracks above and below.
Here is a demo I made:
To mix in more video and audio clips at the same time to different effects depending on what you want.
Since you are new to video editing you really should click the Tutorial button on top of this page and follow all the videos that are listed on that page. That will show you what you need to know to start doing video editing and understanding Shotcut. 